Always have a good back-up plan, or a "Plan B" in the event first choice fails. The only one you can truly depend upon is YOURSELF. Make yourself truly 100% self-sufficient, then when the pleasant surprise come along ... like good working free wifi, it's a real treat!
I am not a full time RVer, but we do go camping a lot, and we always take our computers and Iphones. We have to stay "connected." But we also do not depend upon someone else's service. We use it when it's convenient, but we do not "depend" upon it. And we've been to many, many campgrounds that did not have wifi, or if they did it was really bad.
However, I do agree, if a campground advertises an service, it should be available and working and reliable.
We once stayed in a motel specifically because they had a swimming pool. (it was in the middle of the winter). Checked in, paid, and then found out the pool was closed. They had a problem that took it out of commission for quite a while. When I check with the management, they just shrugged me off. I think they should have let us know up front and then given us a couple dollars off the price because the could not provide all the services they advertised.
Actually, if they would have told us this before checking in, we would have gone to a different motel. We REALLY wanted the swimming pool.