I wasn't expecting a fight when I published a piece about Sam's Club's in-store retail media success. The article detailed their measurement capabilities, their parking lot activations, their member-level attribution — coverage of a US retailer executing well on store-based media formats.

The pushback came from across the Atlantic. Multiple retail media leaders argued that in-store media has been operating successfully at scale in their markets for years, that the US percentages I cited didn't reflect European reality, and that perhaps I was missing the bigger picture.

They had a point. Here's the data that sparked the conversation: strip out Amazon's dominance and in-store will represent only 3.3% of non-Amazon US retail media spend by 2029 (EMARKETER). But several European networks operate with in-store representing much larger shares of their retail media revenue.

So what's going on? Are other markets simply ahead, or are these markets so structurally different that comparison is misleading?

Both. And understanding why matters for everyone in this industry, regardless of geography.

Think of it as natural selection. Retail media markets evolved under quite different environmental pressures. Like any evolutionary story, the species that emerged reflect the conditions they adapted to, not some universal blueprint. Some of those pressures are hard structural constraints. Others are organisational habits that calcified into "that's just how we do it here."

Breaking down the characteristics of each reveals opportunities both markets are missing.

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The Structural Reality

Some differences between US and European retail media aren't about sophistication. They're about legitimately different selection pressures.

  1. Robinson-Patman compliance culture. US suppliers and retailers have long operated under Robinson-Patman compliance norms around promotional allowances and resale-related support. This Act, which the legal teams within various companies seem to interpret differently, has made some brands cautious about shifting trade-style funds into retailer-specific programmes. This caution reinforced an organisational separation between trade spend and retail media spend. The upshot: US networks faced a harder challenge pursuing entirely new budget pools rather than tapping existing supplier relationships the way European counterparts could.

In France, for example, retailers provide "counterparts" when negotiating with suppliers — something of value in exchange for their money. As Guillaume Mounier, Global CMO at Unlimitail, told me: what historically functioned as trade marketing got reclassified and professionalized. Retailers moved these assets from merchant teams to dedicated media teams with proper measurement and attribution. Different regulatory environments, different go-to-market strategies.

  1. E-commerce penetration created path dependency. When digital commerce scaled first in the US, as Drew Cashmore, Chief Strategy Officer at Vantage, noted in a recent essay, "every retail media business inadvertently positioned themselves as a direct competitor to Amazon and Walmart." Europe's path diverged. Mounier described how European retailers had been monetising in-store advertising for years before the term "retail media" existed — they just didn't call it that. Because e-commerce matured later, retailers maintained and professionalized their in-store infrastructure rather than pivoting wholesale to digital formats.

  2. Scale and concentration drove format monoculture. Amazon and Walmart collectively own roughly 85% of the US retail media market. That concentration created a self-fulfilling ecosystem where the sponsored product ad format rules the roost — a format where those two mega-retailers happen to excel. Like an invasive species crowding out biodiversity, the dominance of one format discouraged experimentation with others.

Europe's fragmentation forced different adaptations. Carrefour operates across multiple countries but can't standardize product assortment — what sells in Spain differs from Poland or Germany. "The fragmentation of retail media networks is a consequence of different countries and different types of retailers," Mounier told me. European networks had to collaborate and differentiate — they couldn't simply mimic the dominant predator.

  1. Data regulation shaped what's possible. GDPR makes leveraging customer data significantly more complicated in Europe, especially for off-site audience extension. That's slowed some of the more aggressive data-monetisation plays we've seen in the US.

  2. Geographic density changed in-store economics. Ricardo Belmar, a retail technology adviser, points out how the rollout of digital in-store media outside the US was different story, primarily because of scale. “For most of those retailers, the number of stores was smaller, so the capex was lower for the hardware." High store density in urban European centres might make screen deployment more economically viable than across America's car culture and suburban sprawl.

Self-Imposed Limitations

Not every difference is structural. Some are organizational choices that could be challenged — habits mistaken for habitat.

  1. Internal P&L warfare. Cashmore's detailed history of trade vs. shopper vs. brand budgets reveals how US merchants fought to keep supplier dollars on their P&L, creating battles between merchant teams and media teams. "The biggest behavioural challenge within retail — separate P&Ls and misaligned incentives," he writes. This is an organisational choice, not a market inevitability.

  2. Capital investment appetite. When digital signage technology emerged, US retailers hesitated. "IT orgs were the driver for bringing in the tech, but CMOs needed to own the content and the management of it, and it all just sounded foreign to most of them back then," Belmar recalls. Many European retailers invest in physical infrastructure themselves, while US retailers outsource in-store marketing. The pattern stuck — not because it was optimal, but because organisms tend to keep doing what got them this far.

Why This Matters Now

US retail media growth is maturing — 15.6% in 2025 versus 25.1% in 2024, according to IAB data. That deceleration puts pressure on format innovation. You can't keep running the same playbook when the environment is shifting.

Europe's strength in physical formats — the in-store experiences, the touchpoints where shoppers are actually in proximity to products — represents an accidental strategic hedge against a future where AI-enabled shopping pulls product discovery away from retailer websites. In-store can't be intercepted by a chatbot.

Some European markets are already responding to fragmentation with consolidation. Unlimitail's centralised model is projected to capture 35% of the French grocery market by 2027. That coordinated approach to scale offers lessons for US mid-tier networks still going it alone.

As Cashmore argues in a recent essay: "Europe built the foundation for Retail Media 3.0 — the most difficult piece first. With those philosophies and strategies, it's working backwards to rewrite the narrative around the true value of this thing."

Different species, adapted to different environments, facing the same shifting climate. The retailers who thrive won't be the ones who insist their market's evolutionary path is the only valid one — they'll be the ones who study what other ecosystems figured out and adapt before the environment forces the issue.