I think it would be nice to have tethering for free, but providers have every right in existence to charge extra. You pay for your phone's internet. Not your computer or whatever else you want to tether. You agreed to this when you bought it from the provider in the first place. They have separate devices and contracts for that.
I dislike that providers like Verizon and AT&T charge out the ass for tethering. That's what has left a stale taste in my mouth, but I still dislike when people think that just because "they're the consumer" - anything they say goes.
I guess bandwidth is thaaaaaat expensive for them
It's like buying a car, you bought the car and some gas, but your friends cant ride in it, because you have to pay X amount of $ each month