I suspect people also tend to get busted for this sort of thing when the cops get called for some other (possibly related) reason, e.g. you're doing drunken donuts on your property and the neighbor calls the police because you're disturbing her with loud music.

In most places the cops would probably tell you yes, indeed, you can get a DUI for driving drunk on your own property, so turn off the radio, go inside, and we'll call it even.

When you're dumb enough to start mouthing off at that point, that's when you get the DUI.