High speeds are not an added feature of these vehicles. The power output required for practical acceleration also affords sustained high speeds. To prevent those speeds, manufacturers would have to add speed governors, which Americans would not be delighted to pay for (paying to have their freedoms restricted by bureaucrats, of course). Even if they came standard, speed demons could easily remove a governor.
My understanding is that vehicles already have speed governors that constrain them to the max speed rating of their tires.
(I'm not really trying to be on the opposite side of this argument though. If speed limits reflected the speeds most traffic goes, police themselves followed the speed limits, and disrupting traffic by dawdling in the middle lane stoned or with AI missile mode engaged were a law enforcement priority - then maybe I'd believe. But as it stands speed limits mostly serve as an excuse for cops to sit around playing candy crush until they selectively hassle a motorist)
