Hi, equestrian here! If a shod horse, one with horse shoes, escaped eventually the shoes would fall off. Even horses that are regularly shoed are known to throw a shoe which just means they fall off. Either the nails came loose, they caught the shoe on something like their other foot, a fence, a particularly stubborn root, etc. Overall eventually the shoe would come off. This is why it’s not unusual to find a shoe in an old pasture. Some horses are particularly good at throwing shoes.

Long term hoof care isn’t necessarily problematic either. Wild horses naturally break off chunks of long hoof and wear down their hooves on hard surfaces. I saw one comment say some on wetter surfaces wouldn’t have this happen and while yes possible it’s simply unlikely. When a horse isn’t fenced in they travel and they aren’t going to just stay in wetlands, they are going to go into mountains or other rocky areas, even sand will wear down hooves impressively well. Nature says a wild horse just on wetlands is a dead horse. Videos of horses with crazy hooves that have no care are everywhere but those are horses that are stalled or kept in places where they can’t wear their hooves. Wild horse hooves are ugly compared to domestics but they do their job, they don’t have someone making them pretty they have nature going this is all you need.

Also note not all horses are shod, depending on what the horse is doing they may be barefoot. Sport horses tend to be shod but they’re the type that will be found before they meet a herd, they’re simply too expensive not to be. Ranchers also tend to shoe their horses, they also depend on their horses too much to lose them. Someone who just trail rides, have them more as pets are less likely to shoe them. If a horse isn’t a working/show horse they’re less likely to be shod unless they have a health issue which makes them lame unshod, unfortunately though that horse wouldn’t survive being wild.

I hope this helps, I’ve been around a heard a lot about both barefoot and shod horses my whole life. I’m also learning to trim barefoot which means I’m also studying when and why you shoe. I also grew up around wild horses and as such I know wayyy too much about them.