Here's my guess, your HOA has subcontracted the parking sticker validation duty to a towing company. The tow truck driver comes in and looks for anything and everything that doesn't have a sticker and tows it. It's not in the towing companies interest to give you any warning. That's not how they make money.
We have an HOA here, but they are great. Fees are only $300 per year and the HOA runs the marina for a profit covering most of our neighborhood expenses. No trashy houses, everything runs smooth and I, personally, have never gotten a warning on anything. I wouldn't have it any other way.
Peace is our profession (war is just a hobby)
"I've become quite used to people around here misrepresenting my positions."
- Cavalry Doc