It helps if you look at scale. The whole of the European Union has 448.4 million people living in it. The USA has 331.9 million people living in it. You'd think that this would make them similar given that the EU is made up of a confederation of sorts of 27 different countries and that could be compared to the US being a confederation of 50 states.
The problem with comparing them this way is that, for the most part each Country in the EU is still a sovereign nation. They have their own armies, their own GDP, their own trade deals, their own governing bodies. Their strength in being a union comes from the fact that they are sovereign nations who have banded together.
The states aren't sovereign nations. They'd like to pretend they are. But all their laws, all their provisions for public health, public safety, home land security, border control etc are beholden to the federal government and its two party system. Meaning their laws can be struck down as unconstitutional. They get funding from the federal government. Aid from the federal government. Social programs from the federal government. The federal government has a say in education, housing, the environment, natural disaster relief.
The EU isn't really set up with way. When Switzerland wants to pass a law, they're free and clear to do that no harm no foul. When the EU sets a goal (like GDPR) it's up to the countries involved to decide how to implement laws and policies that would allow for that goal to become reality. In the US it happens the opposite way. The federal government makes a law. Then the states create legislation within the bounds of it.
And the main answer is that it's harder to buy a bunch of different countries than it is a couple of senators.
We're talking about Economic Committee vs a whole Federal Government.