It was a joke to call it a National.
Many of the MX tracks are not open except on a race day. Some do not even have race events, only practice. There are thousands of MX bikes sold in CO every year and dozens of shops for support. That makes plenty of MXrs for each track. Thousands of used bikes available cheap. Two AMA race organizations that put on over 50 events a year. Factory support for both clubs that get 400 bikes each even when they run the same weekend. Karts are not the same as bikes in price and yearly maintence. Karting is more kart/engine than driver, MX is more Rider than Bike. 99% run stock bikes, there never is a tear down as a good rider does not need to mod his bike to win. MX you don’t need to spend a wad to be competitive, you need to practice. Karting you need to spend a wad and practice and you don’t even need to be in good shape. MX you won’t have a chance if you are fat and out of shape, they don’t need weights to make it fair.