European companies rebuild software that already exists. Constantly. Give an American company the same choice and it buys the better version and moves on.

The difference comes down to one question: if a vendor breaks the deal, can you make it hurt? In the US, yes, and fast. That one fact changes the math.

It produces what game theory calls a Nash equilibrium. Break your terms of service and you get sued, fast, and you lose. Defection carries a real cost, everyone knows it, and complying becomes the rational move for all sides. The equilibrium is trust. Not the warm kind. The kind you can model on a whiteboard.

That’s what lets a startup build on top of ten companies it has never met. Check the terms, plug in the best thing, move on. You’re not trusting their character. You’re trusting that breaking the deal would cost them more than keeping it.

Europe plays a different game. Courts take years, protectionism favors the national option, defection is cheap and slow to punish. So you don’t outsource. You build it yourself. Everyone half a step behind the best tool, everyone burning their scarcest years rebuilding solved problems. That’s the real tax: low trust forces vertical integration, and vertical integration is a ceiling.

AI doesn’t escape this game. It raises the stakes on both sides.

The frontier models are a third-party service. To use the best one, a European company hands its data to a firm it can’t meaningfully sue if things go wrong. High-trust environments plug in and pull ahead. Low-trust ones hesitate, exactly as they always have. That widens the gap.

But AI also makes building in-house cheap. Vertical integration was a tax only because rebuilding everything was slow and expensive. Take that away, and Europe’s reflex to build in-house costs far less. That closes the gap.

Which force wins comes down to one thing: does the frontier stay rented, or does it become something you run yourself? While the best model lives behind someone else’s API, trust still decides who gets to use it. The US keeps its head start.

It never had more trustworthy people. It had a better-designed game. AI is about to test what that’s worth.