One can create one's own WiFi :-) which can usually cover up to 5 other pieces of equipment/computers. But it is coming from one's own equipment so you control who has access. http://en.wikipedia.org/wiki/Hotspot_(Wi-Fi) It is what the places you are talking about are providing (hotels), only they provide to more people, their customers :-) Perhaps you have seen a little message on the door of restaurants, fast food places, bookstores, etc. that they provide "free WiFi"? We literally have them everywhere in the US.

Generally, the larger and more public a site is, the less secure it is. That's why airport free sites are a bad idea to use.