The outsized pay for software engineers in the US takes into account a lot of this stuff. Would you trade those 100 things for, say, a salary of $75k a year for a senior software engineer, like they have in Europe?

Meh. The rest of the world also doesn't have big salaries for software devs. The US is the outlier.

It's not just the labor regulations holding Europe back, it's the lack of funding due to not having a unified European digital market.

Netflix Europe needs to have 20+ licensing deals. Selling across Europe at a large scale requires interactions with 20+ legal teams. Language and cultural barriers kill a lot of things.

How do US giants thrive in Europe, then?

Because they come in directly giant-sized based on growth in the US. They either ignore European legal compliance until sued or pay peanuts for them to handle all the legal aspects.