MinnMan

They are a menace to the riders and a disturbing distraction to the other fans, whether present at the race or watching on TV. My guess is that if there was an easy way to stop them, the race organizers already would have. But how? They can't put up barriers along the entire course length. They don't want to restrict fans from the course either. The only mechanism would be to eject or cite miscreants, but that would be totally unwieldy- the authorities can't be everywhere along the course, the race goes through countless local jurisdictions, so the restraining law would have to be national in scope.....

I can't see how it can be eradicated in countries lacking severe social controls. I guess they could hold the races in North Korea. There surely wouldn't be unruly fans there.