Technically, it would be possible to create very large WiFi zones, whether free or paid. But since someone gets paid (either on the meter, or a fee for the project) and there is a cost to constructing/installing the equipment to broadcast that signal...it won't happen unless someone is paying.
In the case of the hotel, picking up on rbciao's point about breakfast--have you noticed that the free WiFi and the free breakfast tend to come with the budget chains, while the high-end places charge for both, expecting expense-account travelers to not care? And it's a pure profit item. It simply does NOT cost $10-to-$20 a day for a hotel to provide WiFi, just as you don't pay $300-$600 a month for it at home.