Regulation might have something to do with it but your example doesn't show that imo.

Multiple US labs were taken to court over copyright infringment for their training data. Mistral did the same data mining, but actually the copyright situation is weaker here so it's harder to build a case against them.

I think the capital situation in EU is just worse. A lot of is tied up in more conservative businesses that are reluctant to bet the house on some shiny new thing.