You’re really over simplifying the process of registering them. It’s not as simple as tossing on some lights and popping down to the local DMV. They have off road VINs, off road titles, and insurance is difficult to get. It’s possible to do it if you jump through the right hoops, but it’s far from easy and not to mention the bike they were riding is a 2 stroke so there’s EPA stuff potentially to deal with as another barrier. Getting through all the paperwork to do it there’s still the matter of putting on the right parts to make these street legal which is another uphill battle. You’ll need all DOT compliant parts, a wiring harness to connect it all and someway to power everything which these bikes don’t have. There’s no room for a battery and the stator doesn’t generate enough power for lights and it’s not a stable output either amount other issues.