Drivers licence as a personal ID is not really a thing in Europe. It's accepted at some places, but either passport or your state provided ID-card is much preferred.
Very few Americans have personal ID so if they intend to do business in America, they should be prepared to accept drivers licenses.
Maybe they just don't want to sell to Americans, which is always allowed I guess, but setting up an American VPS provider and not accepting the standard American KYC verification methods would be a rather incompetent way of doing business. It'd be no different from doing business in Europe and only accepting drivers licenses and not accepting passports/ID cards for identity verification.
In the US, DL works as an ID for almost anything other than voting in an election. You can fly to almost any US territory with that plastic card. And it is state-provided ID -- nobody questions that.
And we are talking about 300M people here, which is about 4 times the population for Germany.
If they hate US residents they should declare that clearly on their website, not wasting customers' (and their own) time.
But you don't just have one type of drivers license for 300M people, do you? As far as I'm aware each state has their own. So it's not 300M vs. 80M, but 80M vs. 50x 6M people (incredibly simplified and wrong numbers, but you get the gist). Far more effort to verify each document.
That would still exclude non-driving customers, which means allowing at least one additional form of ID per state - suddenly you have to support at least 100 IDs for US customers, while German customers have exactly 1.
Not sure how you arrive at them "hating US residents", that's a weird conclusion to get to.
Contrary to the belief of a lot of Americans, just because it works in the US doesn't mean it works elsewhere. In the rest of the world a driver's license is used for proving your right to drive and we have a thing called passports for proving your identity. Hetzner isn't an American company so why should they accept American drivers licenses?
Drivers licence as a personal ID is not really a thing in Europe. It's accepted at some places, but either passport or your state provided ID-card is much preferred.