Well, my guess would be that many (but not all) people understand that being able to call an ambulance because Aunt Betty has fainted is a necessity, but being able to chat with Aunt Betty for an hour from your car isn't. Missing a rerun of Laverne and Shirley isn't critical, and neither is having to wait to post those vacation pictures to Flickr. Your coworkers will, in all probability, somehow muddle through if you can't send them email from your blackberry.
The telephone as we know it was the first genuinely instantaneous, worldwide communications medium that anyone could use, it was seen as a necessary component for national security during the cold war, and was built out as such. We've had over a century to perfect it, and vast amounts of money were spent doing so. Despite its origins at DARPA, the Internet as we know it today, although more useful, is by and large less of a basic need, is far more complex, and large portions of it are still built on top of the telephone infrastructure, besides.
I can't help but think that most people understand this sort of thing, and understand that bringing such modern conveniences up to five nines of reliability is difficult and expensive, and people have evidently decided that a certain tradeoff to make such things affordable isn't out of line.
The shorter, more pessimistic version of this is probably, "It's cheaper to suck."