We just last week stayed at a different CG in Milton Wi or we paid less way less than $50 a night (P A). Theirs was 2 hrs and then log on again. Not a big deal for overnight usage. Their system didn't show up as a Tengo site, more like an ad-on thing.
FREE wifi is open to many different ideas of what it means. ie available all over the park, only in office or rec room, one bar one some sites and 5 bars on others, limited access for 1 or 2 hours, or something else.
While internet access is kind of cheap (maybe) for the home user, that is not true for a CG or business. To provide enough bandwidth for 50 or 100 sites means maybe multiple routers etc. Also, it usually means having someone come out to support it when necessary.