Actually, they do.
I've seen some really stupid people let their kids play much too close to the edges
of lakes that have signs warning of alligators. They also lose their dogs to gators
all the time. It's pretty common in all the areas where alligators live.

In Gainesville, on the campus of the Univ. of Florida, is Lake Alice. It's filled with
alligators, and (last I was there) is not fenced. Alligators don't care about fencing.
They go through it pretty easily.

Years ago, I was there with my best friend. We'd been walking the trails in the area,
and stopped to check out the lake.
There were two women with three small children, all standing entirely too close to
the lake. We warned them to back up. They asked "why?", and we told them that
gators can come up out of the water very quickly, snatch whatever prey is closest,
and take it back into the water.
We asked where they were from, and they answered "Tennessee".
They ignored the signs posted all around the lake.
They were lucky none of their kids ended up as snack.

People are so fucking stupid.