There are a lot of military stationed in Europe with U.S. APO/FPO mailing addresses who might disagree. In my case, I wanted to order some items for delivery to my sister in Florida, but was blocked. Fortunately, there are plenty of other U.S. businesses who don't block European IP addresses.
All of those websites (we are talking about e-commerce, so we have names, usernames, addresses, etc.. so PI, PII, and the works), have backends that are subject to the afore mentioned compliance. There's really no way around GDPR compliance, other than banning EU IPs.
Believe me, I am aware. We see over 1 million patients/year, from around the world, and have 40M unique visitors to our website per month. E-commerce is a part of that. So, GDPR compliance has been front and center in my team's relationship with the risk and compliance group for several years now. My point was actually the same as yours: the pain is not in the websites, it's in all the back-office systems.
Well, it is an awfully simplistic shortcut. They could make their website GDPR compliant as an information source, and block transactions from Credit Cards with a European billing address and shipments to European shipping addresses. If you don't have facilities in Europe, don't advertise in Europe, and block orders from and to Europe, you are not subject to GDPR.
The OP poses some questions other than HTML techie questions. For instance, why are hinges at the same level as closets. It appears to me that they farmed out their website organization to people who can code but don't understand the products. Over my 30 years in software, I met plenty of people who could write code but had no idea what to do with it. Big tech is starting to get the message. They are starting to place value on product knowledge and not just the ability to write code. They are starting to value Liberal Arts degrees to work in concert with the Computer Science degrees.
I worked for a company that competed in the real-time financial information. Basically, we ingested all of the quotes for stocks, commodities, forex and government debt from every source in the world. We consolidated it and presented it to our customers very fast (sub one second). One time, we went through a major rewrite of our user interface mostly so our sales people would have something cool to show off. Meanwhile, Micheal Bloomberg was cleaning our clocks without changing his clunky, text-driven, interface a bit. The 'Bloomberg Box' had the same interface using the same commands almost from it's inception and his customers loved it. As he put it, the customers just wanted answers. He used to say that no trader ever went home and said, "Honey, I lost a billion dollars today but it's ok because the user interface was really cool." My point is that just because something can be changed doesn't mean it should be changed. Those Bloomberg customers knew that they could time in the same few cryptic keystrokes and get the same report so it was worth learning what the commands were. On the other hand, we kept re-arranging the deck chairs and just made our customers mad.
Another Bloomberg story (not political). I was in NY once and a sales guy offered to take me to a trading floor. We show up and have to wait for 45 minutes until some guy gets out of a meeting. While we were waiting, a Bloomberg guy shows up and they waved him on in. Inside, the trading floor almost came to a halt. They gathered around this guy like groupies around a rock star. That's because the Bloomberg salesman never showed up without some sort of gift. He always had a little tip or trick or new report that would help these traders make money. We finally got in but the floor didn't notice because our sales guy just showed up around contract renewal time or to help resolve a problem.