Sure it's not legally binding, but if I see >100000 requests coming from 1 IP address within a week, I'm also not legally bound to make that 402 error go away. By having an automated payment mechanism, the two parties could come to an agreement they're both happy about
> there's nothing stopping scrapers from just ignoring them
Feel free to ignore HTTP errors, but those pages don't contain the content you're looking for
(For the record, I don't use HTTP 402, but I noncommercially host stuff and know what bots people are complaining about.)