A major issue is that the UI of touchscreens is horrible and the hardware used is so slow that it makes the experience dangerously bad. I don't have issues using the Maps app on my phone even though that's a touchscreen. I also don't have issues playing music through my phone (accessibility settings help a lot with this). On the other hand, every time I've had to use a car touchscreen I make sure I'm not moving because I have to look at the screen to find the button location and then keep looking for another second to make sure the press was registered.