ask-captain-rainbow-dash replied to your photo: “If horses had a stop sign, I think it’d look like this. Because it…”:

but that implies that our stop signs look like hands, and I assume you mean stop signs on the road so that doesn’t make any sense I’ve never seen a stop sign on the road that looked like a hand

I was more inspired that the pictogram for “don’t walk” on pedestrian crossings.

Also, the only reason why our stop signs are octagonal is because MUTCD wanted a unique sign to catch people’s attention (most signs are rectangular or triangular). A hand-shaped sign was stupid.

But a simplified hoof has a basic yet unique design that can easily be recognized as distinct from regular signs, which is important for the horses because they often use pictograms.

It also makes sense logically, considering that like our hand gesture, raising one’s hoof in front of somepony is a sign to stop.

TL;DR: I’m overthinking this horseshit to the max please leave me be in my tiny hole of random thoughts.