That’s also common at some places in the US. I grew up (in Pony Club) in an area where it was not, and when I started riding again as an adult, I was shocked that the reputable lesson barn wanted me to tack up a loose horse in a stall. A loose, docile, lesson horse. Eating his hay. I’m now comfortable with the practice when I know the horse.
I tried one lesson barn that kept putting me on a (miserable, must have been in pain) horse who was “instructors only” in his stall because he would try to bite and strike people who entered his stall. I had to tack him in a grooming stall that faced a busy aisle with kids and clueless parents. Everything about that situation seemed like a ticking timebomb.
I’m much happier now at a safe, well-run barn, tacking my happy horse, loose in the stall. I still think about that poor guy, though.