Ultimately, this is your concern...Had several cops over on brew day, all nice fellers, some my friends...
Cops are people, too. If the law exists, and you're doing something stupid, they'll respond. If the law exists and you're being responsible, they'll ignore. In the case of "private property" like Home Depot Parking lots, they have a jurisdiction hurdle to address. Unless you're doing something obviously dangerous, they're not going to waste their time...
That said, if something tragic happens, there is also going to be a law on record saying you, as an individual, are not allowed to do that. This would prevent an student from retaliating against anybody *other than you* for putting them on a motorcycle in a public place. The laws make sense, it's what we do with them that decides if they are overstepping or not.