Toilets.
I don’t know about everywhere else, but in central Texas it was rare that any barn had so much as a latrine. They certainly knew what septic tanks were, but those were indeed different times. Real handle-flushing toilets were low down the list of appurtenances one might add to a purely functional horse barn. Not every rural gas station had toilets, either. I guess the bushes were good enough. Also people didn’t consider it necessary to drink as much liquid as we do now. I think we were probably dehydrated much of the time, but didn’t know it.
Running water. Didn’t have that either, not so much as a hose. The horses drank from a pond. Horses were not kept in a barn for any length of time for that reason. After a ride, horses were groomed rather than hosed to get the sweat off them. I remember that after a riding lesson, once all the horses were groomed and turned out, they would all file down to the pond for a good drink. And they all had different drinking behaviors, that was interesting.
I’m not sure there was so much as a well on some of the properties I frequented. Unless they had a windmill drawing water to fill a stock tank (usually would if there were cattle on the same pasture). Unless someone actually lived there. We used to bring drinking water in gallon jugs.
Electricity. If you wanted to feed before sun-up, bring a flashlight - a big one.
Honestly, we didn’t think much about it. The conditions were par for expectations.
I do not think many riders today would be willing to ride at all without working toilets, running water and electricity in the barn. Plus population density has increased such that many barns are on city water anyway. Those that aren’t are supplied with wells, septic systems and rural electric providers.
Although day-trailering makes those old habits handy. 