We had a big incident here maybe 2 months ago. Massive flash mod of eeeebs through to unregistered dirt bikes on a sports field (up yours sportsball) ripping skids etc. While I am confident the cops could have nabbed a few on the day without issue, the incident juat looked like (and was reported as) out of control punks ruining the world. While news died off pretty quick the cops did round up a few easy targets after the incident.
I maintain the solution is enforcement at the import/distro/retail level. Hit the bottom line of those clowns before the bikes hit the street and supply will dry up pretty fast.