I ponder this kind of things from time to time. This one makes a very enjoyable puzzle because it is extremely simply to move people on a conveyor or a rolling platform but amazingly complicated to get them on and off if you want to run it at any meaninfull speed, absurdly complicated.

My mental gymnastics is mostly trying to mobilize an entire city with the concept. I see some research suggesting there is lots of room between walking and driving distance. Bringing a bicycle also has its down sides.

Because getting on and off is already so difficult one tends not to notice the other problems with the tech. A simple crossroad is already a problem.

Moving fast is no issue for the more athletic passenger without luggage. It is also the most useless device to them. People with mobility issues don't have to get on but they do have to cross the road.

You would want to slow down or stop the surface, put a fence around it, you would want chairs, a roof would be nice, perhaps walls so that you can further control the climate. And then you have a bus, metro or tram. (haha)

One cool variation (not my idea) was to have a moving platform fromwhich to get in and out of a moving train, tram or metro. You could also make vehicles that connect on the sides. Those would have lots of fragile moving parts and potential dangerous situations if they fail. I see a night train misaligned with the station one time with the last door opening above the entrance of a pedestrian tunnel. A drunk guy almost walked out into the 5 meter drop. That seems preferable over falling between two moving trains.