It's pretty common to buy/beg/borrow an old cell phone and just use it over wifi. Especially kids or anyone who is tight on money. Food/water/shelter ranks much higher than cell service and monthly server + Data plan (required for signal) isn't cheap.

Yes. In the USA, people use the free library computers. In foreign countries, people rent computers in cyber cafes.

kids at home could have tablet without SIM and use signal to communicate with parents away from home