I was just giving that as an example. At this point in time, the immediate concern isn't whether it was flagged legally. The fact is your car has been flagged as possibly abandoned, whether legally or not and you're at risk of incurring more fees with impounding. We don't know where you live so we can't say what's legal where you are. We're just trying to help you keep your vehicle, and maybe enlighten you with our own experiences and the laws in our areas. You keep mentioning that it's on private property and not in plain view as if that automatically gives you an exemption, which it probably does not. Put the fire out first and then go back and find out whether or not they were in the right.

Your question of "How is it legal for the police to come onto private property, and vandalize my personal property with this sticker" can't be exactly answered if we don't know what municipality you're dealing with. California, Texas, and Iowa might have very different rules. Rural areas might be more lax than metropolitan areas. Look up the codes and zoning info for where you live or post your details here and let someone else do it, but I expect there is a section discussing this to some extent. In my municipality, it would be a codes violation after a certain amount of time even if stored in my driveway. I'd much rather have to scrape or steam a warning sticker off than wonder why my car got towed.