I don’t think the problem is “no one to watch them ride” as “for safety reasons, someone should be on the lookout for you if you don’t return”. I ride late at night when no one is around because I get off work at 7 pm at the earliest. I make sure to text/tell a friend that I’m getting on my mare and if they don’t hear from me in 30-45 minutes to check-in. Then I let them know that I made it without issue. Maybe I wouldn’t be as vigilant if my mare wasn’t still young and we were just walking around. But I’d like to think I’d always try to be as safe as I could.
If I get injured, help wouldn’t be coming for 10 hours. I see no reason to risk that unnecessarily. It’s just so so easy to get hurt working or riding with horses! Knock on wood, the worst I’ve ever gotten was a bone bruise but it sobered me up on working alone. One of the loose horses in a pasture got too antsy and tried to double-barrel me as I was catching my horse. Hoof glanced off the point of my elbow and I lost feeling for a bit. There was 0 cell reception down there, so I went up to the BOs house to tell them. They weren’t home (and didn’t wind up coming home for 5+ hours). It was a 2-3 hour drive to the barn and everyone who knew I was going wouldn’t have expected me home till near dark. Had that kick shattered the bone in my dominant arm, or even just hit a nerve, it would have been very bad.
It’s one thing to choose to ride alone on your own property and get hurt. It’s another to do it on someone else’s.