One of my points is that quite a lot of sites don't currently do any international transactions with site visitors. They make their money selling ad space. Their transactions are with a small number of ad networks, probably in the same country.

The site's lawyers and accountants are most likely just trained in dealing with in-country transactions.

If the site start directly charging international crawlers it is then adding international transactions and will need accountants and lawyers who can deal with that.

Big sites with a lot of revenue can probably handle this fine. Smaller sites are much less likely to be able to deal with it.

There is also political risk handling it yourself because some counties are viewing AI development similarly to how they view weapon development, and I would not be surprised to find that some countries will view selling AI crawling access to certain other countries as violating sanctions.

Thus for most sites that aren't already engaged in international commerce they are probably going to want to go through a middleman to sell crawler access even if cryptocurrencies are used for the payment system.