I'm still waiting to see what the opposition is going to do when they get organized. If you thought Uber was a threat to cabs, they don't hold a candle to a fleet of self driving cars with an NFC payment option.
[1] Which was of course a challenge for the Segway
That said, it wasn't legislation that made Segway fail.
True, but it was pretty contributory. For much of its 'early adopter' period people had no idea whether or not they would get a ticket for riding one on the sidewalk, and then later the knew that they would in most places. That certainly mitigated sales significantly.
Similarly if self driving cars were available today and you could only 'legally' use them in California and Nevada in self driving mode, and they were "probably" going to be illegal most everywhere else, that would make it hard to sell them.
Sometimes governments actually get it right.
Truth is there isn't enough space for sedgeways over here. Pavements too narrow, roads too littered with parked cars.
But I can see how in the vast empty sidewalks of some suburbs that riding bicycles on the sidewalk is a good idea, and did so myself when I was a child.