Couldn't a driver engage TACC by engaging FSD and giving the steering wheel a good yank? Unless they changed it, one of the biggest flaws of Autopilot and FSD has been that it's easy to disengage Autosteer and the car won't try to reengage it. It's also incredibly easy to do by mistake.
It would be tough to use the configuration to activate TACC since the car must be in park. It was already a problem because there was no way to switch between FSD and Enhanced Autopilot without stopping the car. FSD takes away the button to switch to standard Autopilot and had they left that, I probably would have kept FSD enabled in the configuration. But Enhanced Autopilot does what FSD does on highways and has a button for stretches where I just want the car to follow the road without second guessing me.
It's a moot point for me because I gave up after six years of not having FSD and got rid of the car. I still have a Tesla with Autopilot, but I mostly drive a Lucid. And it's a pleasure being able to override Autosteer momentarily and having it kick right back in when I let up on the wheel or finish a lane change.