My sister was in the hospital less than a day with her first one. I don’t know about the others, because she and I had married and moved in opposite directions.
Unless there are complications, it’s not unusual for a 24-48 hour stay. Mostly, they just want to make sure everything is healing properly.
As far as I know, pregnancy is not an illness. Women delivered babies without going to doctors for a very long time? I understand there can be life-threatening complications, but I don't see why we use up valuable hospital space with maternity wards.
I think if I were going to design a system from scratch I would encourage the development of birthing centers that were located near hospitals and had emergency access to those hospitals when a life-threatening emergency occurred. But for the normal childbirths it would be far less expensive and far less stressful than going to a hospital.
If I were running such a center, I'd have lots of thick socks, warm bathrobes, skin creme, places for siblings-to-be to play, and a good atmosphere for friends and family to visit the laboring mother right up until the time when clothing becomes a bad idea.
For the record, Mrs. ArGee wouldn't believe she was in labor with our first, then took a long time to get ready to go. When we finally got to the (military) hospital she was 7cm dilated. Our son was born within 2 hours. THAT's the way to do it. Even though the hospital was positively barbarian with stirrups and silver nitrate and all sorts of horrible, antiquated things, it was the best L&D experience she had because most of it was at home.