I just wanted to point out that the Maasai Mara was the busiest of all of the Kenyan parks that I visited (and probably of all Kenyan parks full stop), though Nairobi National Park wasn't so far behind with such easy access to people from the city of Nairobi itself. I think I passed one other tourist car in Nakuru National Park, and two in Hell's Gate as well as a few people on bikes. And of course everywhere else, the laws with regards to sticking to the roads were in place.