You are comparing Anthropic obtaining public data from the Internet to Anthropic leaking their trade secrets and having them distributed by third parties.
Like slurping my open source projects, while completely disregarding their licenses. In my case, I'm particularly annoyed by the violation of the spirit of *GPL licenses. So they're no strangers to abusing licensed code (in technically probably legal, but untested in court, ways).
If you believe any data that is publicly accessible is fair game regardless of licenses, then by that definition, Claude Code's source code is included.
Except Anthropic published the Claude code source code themselves, while Books3 was not published by their original authors.
Either you are being naive AF or you are actively trying to spread discontent. I hope it is the former.