Because cell phone plans suck.
Agreed.
And this is ultimately why people stick with POTS.
I press a button, say "call " and then either click the number or say which one it is.
Doing so requires a smartphone, and in Slashdot's home country, the top carriers (Verizon, Sprint/Boost/Virgin, and AT&T) require all smartphones to be activated on a data plan. A lot of parents don't want to pay for a data plan for each of their single-digit-year-old children.
Call is ringing within 5 seconds.
And it's using up two minutes on your plan per minute that you're connected: one for the caller and one for the callee. A lot of families don't want to pay what carriers want to charge for unlimited calling because they don't make enough outgoing long-distance calls for it to actually be cheaper than POTS.
Why would you make so many calls to other rooms in the house. Stand up, walk around
Not everybody has that luxury.
Stop dropping your phones.
Good luck getting your single-digit-year-old children to do the same.