For what it's worth, I'm a Verizon customer, and have been so for over 10 years. I started tethering on Windows Mobile, then Android, and now on iPhone. I (unfortunately) have Time Warner Cable for internet at home, so obviously I don't do much tethering there. But when I'm anywhere else that I need internet on my ipad or laptop, and there's no free wi-fi around, I tether. There have been months when it's exceeded 10 GB in a month.
I've never paid VZW for any additional tethering, nor have I ever received any notice or been throttled. I pay for unlimited data on my phones (currently an android phone and an iphone) , and for the $160+ / month I faithfully pay Verizon for my 2 phones, I feel unlimited really should mean unlimited. If there is a limit, don't call it unlimited, call it the "5GB a month and then we throttle you/charge you more" plan.
For what it's worth, I took my plan from $90 a month for a single phone to $160 a month for a 2-line family plan, partially to get an iPhone before my annual upgrade was available, but also to have a line that I can use for tethering even when I need to use my primary line to talk (people still do that on their smartphones?) So essentially I'm already paying an additional $70 a month for a data device; considering that I average less than 10 gigs a month, I think VZW's getting a pretty fair deal here. I would be willing to pay full retail price for a LTE hotspot on one of my lines if they would allow me to keep my grandfathered unlimited data on the hotspot line, but since they won't, I will eventually drop the second line and get a Clear Wireless 4G hotspot ( @ $45 a month for truly unlimited data) and then I will cease tethering on my Verizon phone for the most part, except in rare cases where I left my clear unit at home or in the car and I need a connection quickly.
I think all this a la carte pricing on internet access when the average person owns so many different devices that could benefit from being connected is shortsighted. What would make much more sense is to charge me one price for ALL my internet access and maybe a nominal monthly charge for each additional device that needed it. Considering what I pay for home internet access and my two phones, I'd be willing to pay VZW $100-$120 a month for "universal" internet access with an additional $5 / month for each of my 2 phones and ipad (or 1 phone, one hotspot, and the ipad) if they gave me unlimited data across all devices and 4G speeds on the wireless, 20GB up and 10GB down at home. That's not including my wireless voice and txt messaging. I'd ditch the Time Warner triple play package I have now and just get cable only (and only because my girlfriend can't do without it; I'd rather give them the boot altogether and stick to itunes for shows) Instead VZW gets $60 a month to provide internet to my 2 phones, soon to be $30 for just one when I switch to clear for tethering. But then again they're a big company; the best of the big wireless carriers in my opinion, but still, why do I expect them to be forward thinking and capitalize on the increasing onlineness of the average customer across multiple devices? Any fresh-outta b-school MBA knows it's much cheaper to cross-sell/up-sell an existing happy customer than acquire a new one ...