So why would someone think this sign is enforceable?

They also explain the TABC signs. So why would there ever be any question about:

Here's another. Why there would ever be any question about this sign is what's beyond me.

There are also slocations that are off limits, all the time. It's cut and dry.
I've never run in to a situation where I had any confusion...I have seen the 4413 (29ee) signs in SAT and I walk right by.
Maybe a "Is this sign legal" sub-forum is in order...