Originally Posted by
2manybikes
People do ride 4 wheel quads. You may not have any where you live, but It's a big world out there.
Each extra wheel slows down the vehicle and adds complexity and cost. You don't have to balance a trike like a bike, so the extra wheel on a quad is more of a drawback than a benefit. Three wheels give you what you want with one less wheel than a quad. No reason to add a fourth.
Isn't having two wheel tracks instead of three a reason? What do you do on a trike if you're approaching some broken glass? Very hard to avoid on a trike, I would think. Easier on a quad.