>Tell users you are being logged on website.
Frequently not legal
>Put alert warning that account has logging enabled
See above. Gag orders a problem with government in general. They do have a warrant canary page though, as well as a transparency report.
https://protonmail.com/blog/transparency-report/
>Change the service so collecting logs is not possible
You mean stop serving HTTP and MX requests?
>Stop adding captcha to tor users login because you want to identify users
You mean let bots brute-force my password?