Well, in theory, this is true for any country. If you ship widgets to a customer in Madagascar and those widgets violate some obscure Malagasy law you never heard of, the Malagasy authorities could prosecute you. But if you didn’t have any assets or employees in Madagascar and never planned to travel there, and if there was no law or treaty in your home country that let them extradite you or attach your home assets, then you could just put their warrant in the trash.
Except I don't have a warehouse in the United States. All I have is widgets located in Europe, I put them in a box and I ship them using parcel post to anyone anywhere in the world.
Yet you are saying that I am now beholden to US law because I interacted with a customer located in the United States ...
The question is not whether you have to comply so much as what they can do. If you are selling a physical product it has to get into the US somehow (unless you drop it like a drug dealer by airplane of course). So you are either using the postal service, UPS, Fedex etc or it's coming in at a port or some other method. One way or another, separate from a domain name, there is a way for the government to stop that product from being sold here (of course you can alternate your delivery methods and obscure who you are but that's another story).
I regularly get letters from overseas companies offering to put my trademarks into "International Trademark Registries". They charge $1000's of dollars hoping that someone's bookeeper will be fooled and pay. They very very clearly violate US laws in many ways. Yet they still keep coming. The government doesn't go to the trouble of attempting to shut them down (they could block wire transfers or credit card payments etc but the don't). It's simply not important enough to them.
This idea that just because something can happen it will is ridiculous.
It's also breaking the law to go 56 mph in a 55 mph zone. But how many people have received tickets for doing that?
Sure, they can hold my shipments and destroy them, and I'd have to refund my customers money, but that wouldn't mean they could bring a lawsuit against my company because I was shipping something completely legal in my country to a country where it was not legal (if I had known, off course it wouldn't matter, but how can I be required to read up on US law to run my business).
