I see a lot of them here on the West Coast. Of course, you tend to see more of what 'you' are driving on the road. Besides Lance being in CA; instant proximity; my guess is there is a very long 'camper season' here with a whole lot of natural features and beautiful places to visit any time of year, that are perfect for a TC
The N.P.'s have an old 20 or 22' limit in many of their camp grounds. That lets out,
1. Moho's
2. 5-er's
3. most Class C's
4. leaving small class B's and Truck Campers as the RV of choice that will fit and work without hookups.
regards, as always, jefe