I've seen plenty of folks going well over 65 mph on the west coast towing TTs, including factory delivery drivers.
The problem as I see it is that nobody tells a TT buyer that ST type tires have a max. speed rating (most of them) - neither the TT manufacturer, the dealer or insurance company. Should at least be a sticker on the exterior wall above the wheels. Owners also aren't being informed about the importance of having correct pressure in the tires and not overloading them.
Went camping a couple of years ago with a couple we know and they stopped at our place before we headed out. I asked him if he'd wanna maybe check his tires. All 4 LRD TT tires were down 10-15 psi and they'd never checked the pressure in the 1 1/2 years they had owned it. Then I asked if he knew about the 65 mph speed limitation - nope. I bet if you did a survey in a CG this would be the norm and not the exception.
With all the mountains & hills and twisty roads up and down the west coast, many drivers slow way down even when they could easily take the curves at 65 mph and they're often afraid of oncoming traffic and/or losing control and move onto the road shoulder where something could be picked up and puncture a tire. Some even do that on straight 2-lane secondary roads.
Maybe TT owners/drivers should be required to pass an exam and road test to get licenced to tow a TT....