Normal people didn't ride horses everywhere. They weren't used like cars. I'm so sick of this analogy. People walked places. If it was too far to walk you used a horse drawn bus/tram. If you had to much to carry you used a horse drawn truck. Every single person wasn't riding an individual horse ten minutes each way to buy groceries every day like that do now with cars. Cars unquestionably kill drastically more people than horses ever did or even could. Tens of thousands a year in this country alone! The leading cause of death for children and young adults!

We're pretty off track given that ya'll are nitpicking the metaphor rather than the actual topic, but claiming that horses were never common doesn't really have any connection to the claim that per-mile-moved / per-human-carried, horses are also dangerous.