What you see in those cars is not FSD, but Autopilot that comes with every car. Autopilot is lane keeping + traffic aware cruise control plus a few small features like green light chimes and speed sign detection.
FSD looks very different and you can see everything in the road and what the car is planning to do. There's some good YouTube channels where they test different versions of FSD in different situations, AIDRIVR does a good job, eg https://youtu.be/rMDNFLsXFEU?si=SHWAm24ZY3psnO4Z&t=136. Nice thing about those channels is you can also look at old videos and see the rate of improvement.
I had FSD for one month on my car and it was really impressive. There were plenty of disengagements, but they were all what I'd call "quality of life" issues. Car was too hesitant during blind lefts, or advanced lefts, car slowed down too much for speed bumps, it got into turn-only lanes later than I'd like, etc, etc. The hardest part of driving in my town is a 3 lane roundabout where upon exiting the roundabout you have to very quickly and confidently change 2 lanes in order to get on the highway, it handled it with ease. Overall, I would not buy it today, but didn't see any reason why they can't solve the issues I saw.