This is not the case. If you operate in the USA or any EU country, or any other, you are subject to the laws and authorities of those countries. It is another thing if those authorities try to send you a request and all they find is an email. But what you say is like saying that an illegal immigrant is not going to answer to the authorities of the country where he is because he is not from there.

Furthermore, little by little, as regulations advance, mixers will be required to have a licence, which will make them lose much of their meaning, or they will be declared illegal, so they will not be in the legal limbo they are in now, and for example, advertising them here will be illegal advertising, which will not be allowed. But hopefully that's still a few years away.

So, with respect to the OP's point, mixers can either cooperate, potentially losing customers (albeit for the right ethical reason), or not cooperate and potentially end up as a Chip Mixer.