The problem is the laws regulating automatics are absolutely idiotic, and automatic weapons are 100% legal to own, just kind of expensive. Not like "need to be a multi-millionaire" expensive, but "can afford to pay cash for a late-model used car".
Like most of our half-assed regulations, it doesn't actually do anything other than making it pay to play. We don't actually want to do anything that might prevent cops and their buddies from having a monopoly on force, so basically every gun law is moot for them anyway, even if they're buying them as private citizens.
That's one of the biggest concerns I have with the way we regulate firearms (among many other things) in the US, because they clearly aren't made with a mindset of "X thing is bad for society as a whole, we need to do something about it", it's "X thing is totally fine if you're in our special club, but the plebs are not allowed to have it.