Exactly, and by design: each user is allowed to set their own tab width and not mess everyone else up.
Like 8 space tabs? Go for it.
Want only 2-space indents? Just update your settings.
The semantic mean of a tab is “indent” - it should be up to each user what their idea of an appropriate indent width is.
Cheat detection belongs on the server, not using up your CPU cycles and power and exposing you to serious security risks for the vast majority who don’t cheat.