Don't get me wrong. I think the laws are silly.

You can convert a 134a system to hydrocarbons, but not a system using R12. Very silly. Sillier so if you consider the fact that it is easy to put HC-specific fittings on the old R12 systems, and very hard on a 134a aystem.

You can buy canned "air" which is pure 134a with the intention to vent it all to the atmosphere, but you can't vent the same chemical once it is sold for an automotive air-conditioner application. Very silly. Tons of the stuff are vented legally.

The problem isn't that the laws make sense. The problem is that while you're unlikely to get caught, the fine is quite severe if you do.