Whether someone logs in or not all devices on the internet can be traced instantly. The technology is there and used by online shops, banks, etc.
They can monitor and look into anything.
Your location is often tracked or given away by " cookies" on your device and the ISP you use, hence you get local adverts cone up. You can disable this but still whatever ISP you use will give an idea.
If you search Maps like google maps then your current location is given away.
Often it's easy to track someone, i.e. If you post here and someone says, I saw a car crash at 5.10 pm today, it may give out your location. People saying weather etc also narrows people down and a quick cross check with the TVL records will give a pretty good idea if you gave a licence or not.
Logging in does tighten thus up, it also removes the excuse of looking by accident, as you deliberately logged in.