Then the network would need to have enough towers to handle everyone's streaming traffic and the cost of that would have to be passed on and eat your savings. Wired networks have lower cost when dealing with high data rates because they don't need scarce shared radio spectrum for higher speeds.

You can already pretty much get what you want by going the other way. Get a fast home internet connection, use WiFi at home and at work and get the cheapest available pay per use data plan for the small percentage of data you use while in a car etc. Doesn't work for people who use a large amount of data while traveling, but that's not actually most people.