As from the other thread, my views are pretty limited on sharing wifi. I am happy to do so with guests overnight, but I am taken aback when I am asked for it by visitors who are there for a few hours. There's a few reasons. Each time I have been asked, it's never, "Oh, would you mind sharing your wifi?" but rather, "what's your wifi password?" There's a difference there to me, and an entitlement that gets under my skin. Also, I always have to wonder why someone would need wifi (unless it's something specific for us during the visit, ex. movie times, google a debate issue we're discussing, etc.).
In the other thread, it was assumed that there might be a generational gap here, and I don't really believe so. I am in my 20s, and I am pretty addicted to my smartphone, but not when I am visiting. I can think of a few times I have even asked for wifi password, and it has really only happened if I am out of country, visiting for a few days. So, there's huge roaming charges involved if I use my data plan. I mentioned in the other thread that my aunt and uncle do not seem comfortable sharing their wifi, so I simply make sure I have my data plan topped up for those visits.
My view in a nutshell: up to the host/hostess, and if they do decide to share their wifi, it is a lovely gesture, and not something that should be expected.