I have a long history with bicycles. I raced road bikes during the late 1970s until the mid 1980s. I then changed my emphasis to mountain bikes and raced mountain bikes into the early 1990s. When I took up skijoring and bikejoring I phased out the bike racing in my life. I feel equally comfortable on a bike or a scooter when running dogs.
Scootering is a much more dog powered sport for competition. Pedaling a scooter has no profound mechanical advantage like a bicycle has. The person who wins a scooter race is a lot more likely to have had good dogs. The winner of a bikejoring race might have good dogs but you can't be sure because the rider may have had a slack line during the whole race.
The popularity of bikejoring races is growing. The reason is that many people already own a bike and use it to train dogs. Far fewer people own a scooter. I would like for more competitive dog drivers invest in a scooter. I would like all race giving organisations to emphasize the scooter class as the pro class for one or two dogs and make the bikejoring class a novice class. Racing dogs should be all about the dogs and not the rig. Pedaling a bike while racing is eqivilant to using a motor on your ATV when training a team of dogs.