If parents want to furnish a dirt bike to their kids, or if older, one wants to ride a dirt bike - let them do it on their own property or on public land designated for that purpose.
Too often parents buy their kids dirt bikes, but have nowhere to ride other than on other's property. And that is not right. Some people even go further and deliberately set out to destroy the property of others, or to harass them for other reasons.
As a father with children that wanted dirt bikes, I did not permit either situation. The source of the problem in my view is that parents that let their kids ride just anywhere they want is that they themselves don't want to be bothered with the time and effort to TAKE them to a proper riding area. Parents too often just want a baby sitter, and sending their kids out to ride their motorcycles and/or 4-wheelers is an easy out.
The source of the problem in not in the misbehavior of the youngsters, but in the lack of parenting. I for one, encourage kids to ride bikes and participate in any other sport they enjoy. I myself am/was a biker. Along with that label comes the responsibility for respecting the rights and property of others. If you can't do both, i.e. ride and respect, you can't do either.