.com domains really need to be more expensive. If the price was $100 or $200 a year, that would significantly decrease the amount of squatting.
Of course, determining whether a domain is really in use or not is hard, and whatever criteria are adopted, squatters will try to game them.
But of course, ICANN and registars make way too much money from these people to do anything about it. Isn't capitalism just wonderful?
It is easy to detect the egregious cases like you describe.
But, not all cases are so egregious. I might have no website on the domain, yet still be using it for email. Or, I might be hosting some sort of intranet on the domain and all the public can see is a login page, with no idea of what content lies beyond it. Or, I might not be using the domain at all, and just waiting for someone to contact me with an offer to buy it. I might even hook it up with email that I never really use (but which redirects to my actual email), and a login page with nothing behind it, in order to make it look like I am really using it. How to distinguish these cases?