> It's not illegal but it's also not required for car manufacturers to give 3rd parties the necessary equipment/parts/documentation required to repair their cars.

This is where you're wrong though. Car manufacturers are required to provide all of that in the EU, because it's a prerequisite to having competition in that space.

It was codified around 2007-2011 into EU laws, but most European countries already individually had laws for this.

How do EU laws impact the US here? From what I hear it's only thanks to these laws that some independent repair shops in the US are able to fix certain things at all, because they can receive tools and such by proxy of the EU (and other places).

The US has similar laws. I used to work for third party scan tools, in 2006 every manufacturer was giving us information. The big companies made them available for "a reasonable price" which I'm lead to believe was in the range of 50000. The small companies gave it away and begged us to support them. (small companies knew that if their car broke down in the middle of nowhere the only mechanic would be independent and so they wanted every mechanic to have a chance, big companies knew every mechanic would want to work on their cars so they didn't care to make it easy)

This would be news to every EU car mechanic I ever interacted with.