Skiing, skating, bicycling, riding, surfing, windsurfing, scrambling, motocross, gliding, hang-gliding, kite buggies, Formula 1 can all be done solo, in fact most of them can't be done in company. List all the saddlers making two man saddles. So why does driving have to be a two man affair?
I have been told that you MUST have a groom to go on the roads in a horse drawn vehicle, yet I have failed to find this anywhere in any legislation. I also fail to see any logic in the idea. It may be true for Carriage driving, a sport started by, and re-enacting the lifestyle of, a group who had servants coming out of their ears.
But back in the great days of Carriage Driving, 99% of all horses were NOT Carriage Driving, they were working with the working classes. Milkmen couldn't afford a groom. Pit ponies went from one man loading tubs, to another man unloading tubs without a groom, footman or postilion in sight. If you carried another person, it was to do a job not hold the animal still so you could get off. That was achieved by Training