If my account was accessed from 20 different countries in a day you can be damn well sure I'd want to be given a heads up too, as it's likely my account has been compromised.
How could something be obvious if you have to check? Lots of stuff you can do in an appartment is illegal, too. That's still no reason for a landlord to install cameras to check. It's just none of their damn business.
It's obvious if a potential customer asks whether your service is good for warez hosting, or if a potential tenant ask whether your appartment is well-suited for getting rid of bodies. Anything where you have to violate their privacy in order to find out just is not obvious, and it's not your job to monitor people's private lives for possible illegal activity (and it is highly unethical to do so--it's what totalitarian regimes do, read up on the GDR's Stasi if you want to know what living in such a society is like).
> If my account was accessed from 20 different countries in a day you can be damn well sure I'd want to be given a heads up too, as it's likely my account has been compromised.
If you want to monitor your own account (or want to have someone, like the hoster, monitor it for you), feel free. It's still none of the hoster's business to investigate it any further without your explicit instruction to do so.
And I must say I find it particularly strange that you seem to find it somehow impossible how someone could use an internet service from 20 countries in one day. I mean, it's the internet, right? A computer on every continent is only a few mouse clicks away. And international teams, either of freelancers, or of employees of a company, working together on projects, isn't exactly unusual either.