These things:
Cities of all sizes appear to have at least one. Most that I see have fallen in to disrepair. Have you ever used one? More than once or twice? Do you know anyone who does? How about your friends over in Europe (they were originally developed by a swiss guy), do they use them with any regularity?
I have a friend from my gym who does parkour to keep up with his 18 year old son. The guy is in his 60’s, and is in better shape than most 20 year old guys I see.
NM
Your link shows a different kind of trail than the kind I was thinking of.
In the link the upper photo* represents exactly what I am asking about.
*I just notice that the pic is from a park ten minutes from where I live. So I am now aware of three of these trails with 15 minutes. [Note that nobody appears to be using the equipment]
I walk such trails, but I don’t use the exercise stations.
But I have certainly seen people doing that, so, yep, people do make full use of these trails, at least hereabouts. I think it’s a nifty civic improvement, and I’m sorry to learn that some have been allowed to decay.
(An exercise station of this sort, if dilapidated, could be dangerous. Bummer.)
There are a few along some of the beaches in Sydney. They do get used, but not as much as they get jogged past.
There’s one along the bike path on the Esplanade in Boston. There are always people using it when I run or bike past.
I use one 2-3 times a week. Primarily the parallel bars and pull/chin-up bars for upper body and core/abs training. I wish the one I use had a bigger variety of stations for parkour type workouts.
Every kind of people you can imagine. Old, young, in shape, horribly out of shape, all races and anything else you can come up with as a descriptive. I enjoy the darn things myself, and the occasional out-and-out obstacle/confidence course and I’m basically 60, overweight, have some health and physical issues and all. I’m smart enough not to overdue it and I have done them for so long that I know the techniques and risks — but I just enjoy the darn things.
We have several walking/running/biking trails in my neck of the woods. Much of our old railroad system was removed and turned into statewide (WV) “Rails to trails” I actually have one that runs right behind my house.
There are no obstacles or additional exercise equipment, but it makes for a nice walk.
Fitness approaches come and go, and this was a trend around here (SF Bay Area) back in the 80s. We still have them, but you don’t see them being built anymore. “Everyone” is joining CrossFit these days.
Or at least they’re talking about CrossFit. Incessantly.
There’s one at a park near here, where I often walk the dog. It’s been there for decades, but I don’t think I’ve ever seen an adult using the equipment (kids treat it like any other playground equipment). I keep thinking that one of these times I’ll go through the whole course just to say I’ve done it, but it’d have to be when I was there without the dog, and I’m pretty much never there without the dog.
This is my experience as well. Light use in most places, but the “equipment” is pretty robust and it’s a nice sign of a civilized society.
There is a pretty tough one on the base in Winnipeg, if anyone wants to give it a whirl. I have done a few “confidence courses” (they use that now instead of obstacle courses) while in training. It’s fun and really tough. The one in Shilo was sort of famous for looking easy. It was not.
In my limited experience with being at parks with workout stations; I have found more of them to be in disrepair than in actual working order. Either through age or vandalism. 
They had these set up on the MUT path along Martine Luther King Drive (formery West River Drive)- a bunch of them fell into direpair and were removed, but they seem to be replacing a few of them.
They’re not doing anything to fix to horrendous condition of the trail, FWIW.
^Exactly what I came in to say.
I use one about 4 days a week. It’s more basic than a ‘trail’, but I love doing body weight exercise. I’m in my mid-40s and most strenuous exercise leaves me sore for a couple of days. Body weight stuff is a lot easier on me.
I will admit that there aren’t that many folks that use it. Plus, it’s really cold here for about 5 months a year. I see a lot of people who’ll do a station or two for fun and then leave, but I secretly hope they’ll like what they did and maybe try to take fitness seriously.