They aren't wide enough, they aren't safe enough, they aren't good enough. Now that ebikes and electric motorcycles, electric scooters (two, three or four wheels), electric skateboards and monowheels are common, we need something better.
Even on a regular old acoustic bike, if you can hold 30kph you are moving far too fast for the standard, next-to-a-curb bike lane. People just don't think bikes can move that fast. But everything can, now.
