And yet, if you’re willing to live without the very newest device, unlimited voice/data are available for under $50/mo. Devices can be nearly free, or you can find a last-generation Android phone or iPhone on EBay.
And no, Biff and Buffy along with the family dog don’t need a data plan, just basic voice to call home in emergencies or whatever.
Also keep in mind that landline phone bills used to be a lot more expensive than they are now. Remember when city calls were metered by the minute, and domestic long-distance was 25 or 50 cents per minute? By comparison, a cell phone (or modern landline, with long distance built in) bill is a pretty good deal.
As far as using my phone abroad — so easy to use a local SIM with an unlocked phone. Or recently, I’ve been buying data-abroad from AT&T and using it with a jailbroken phone for VoIP calls.