Google Analytics isn't better at anything other than their marketing has convinced everyone that it is a must have. If you believe 100% of the data from GA is accurate, then I have a bridge to sell you.
Only legally for the US. Those processes aren't legal for the EU, so the transfer is illegal (for an EU web site).
The problem is that companies with a presence in the US can be forced to break the law of either the US or the EU. It's illegal to hand over the information to the US government, but it might also be illegal not to.
Do you mean, who's stopping them from not collecting personal data? No one, that's the point. If you're not collecting personal data none of this applies and you can serve whatever you want to people in the EU.
If you mean, who is stopping them from handing over data to the US government? That's exactly what this court case is about. They can't conduct commerce in the EU unless they have a mechanism to avoid that, and progressively more strict enforcement gets imposed by courts if they keep trying. (Eventually, presumably being detained if they try to enter an EU country, though I seriously doubt it would escalate that far in practice.)
The government can always just ask. Very little data in the US is protected.
What about the cookie popups, with the "accept" vs. "more info" choices? Is that legal, then?
In all cases where you see a banner for accepting cookies, the company behind it is doing something nasty to the users. (i have yet to see a counter-example to that)
edit: but you can be required to by law. You're right.