It's part of an oligopoly. Let's treat oligopolies the same as monopolies, because they behave almost the same.

57% ios vs 42% android.

But that's not the case in the EU. They are more likely to come after Google.

And the US government has issues coming after monopolies that are US based and bring a lot of money in (for obvious reasons).

If the US starts regulating these companies more it would harm the US GDP. At least in the short term. There is an argument to be had that it could make the markets more competitive in the long term but without a lot of credible threats from outside of the US why take the hit and the risk?

65% is not a monopoly. In fact, we have a real judge that dismissed that argument in the Epic vs Apple case