This isn't why, but it's worth noting that the calls for regulation (from the big companies) are coming now. This is them pulling the ladder up because they're scared of other Western firms taking advantage of the rapid improvement of open source and cheaper models to build competitors at a fraction of the investment. I guarantee you that at least the US will not significantly bind any of the big players, not under this administration and likely not under any.

From Trump at least, the objection seems to be that China wouldn't regulate their industry - but then China could just argue the same in an infinite loop of nobody doing any form of regulation