Yeah that's the only way I could justify paying $30 or more for mobile data, is if I could tether it and get more use out of it.

Rather than be limited to some surfing on a mobile device with a small screen to kill some time here and there.

On a per hour and per megabyte basis, mobile data is way more expensive than the connection you use at home.

Of course, if they allow tethering, they probably couldn't support the increased use of data and would have to raise prices.