We used to see these in Argentina, they were rectangular with a pair of hooks on the underside to hang non-food trash. I was told these were made to keep the stray dogs out of the trash.

This is not the only country to use these. I lived in Nicaragua and they were in all the residential neighborhoods, only square.

After living in and traveling around Yucatan many years, we've not seen any rats. Too many stray dogs and cats, we suspect. Also, dogs make pretty short work of anything edible in these trash cans.

There are two more likely reasons for this design:

1. The inventor was a cousin of someone in the municipal government, or

2. Heavy rains with frequent flooding (especially on Cozumel)

By the way, just because a particular technological innovation doesn't consume energy or require software development, that doesn't make it "crude".

I also think that this kind of garbage collector, which I've seen in many countries, might serve as a safer way to burn the trash, as well as keep garbage off of the ground.

It may be rats in Cozumel, but I first saw similar street trash containers in Chihuahua. I was told it kept the trash from attracting the packs of wild dogs that roamed the suburban area I was staying. This was circa 1996.

That, my brother's wedding, the bus trip down and the broken glass embedded in cement on the tops of concrete walls surrounding family haciendas are indelible memories of the trip.