I mean it's not legally binding in the sense that if you start sending 402s or 403s to a scraper it can just take that as a signal to try again from a different IP address until it works - your servers clearly stated intent that the bot should pay up or go away isn't legally actionable. With enough effort you can chase the bots until they run out of resources, but few people have time to win that battle by themselves, hence delegating it to Cloudflare or similar.