I always strap my flip tops shut and lay the cans on the side, full or empty. Also I strap them down while on the side. Not that I'm paranoid but I got to the transfer station once at 5 minutes to close and they wouldn't let me unload. I had some select words to say and the attendant called the highways cops to report my "unsecured" load. (Two garbage cans on their side were a few inches above the bedrail). The cop did not ticket me since I guess the attendant reports anyone he gets upset with. I now strap them for the heck of it, get there earlier and act like nothing ever happened. Not worth the fuss since strapping only takes a minute or so.
What communist country do live in that nothing can stick up over the bedrail without being tied down?