Many locations that for various reasons have fenced in animals use those so that there can be breaks in the fence for vehicles without the animals escaping.
Edit: but, you know, whatever size is appropriate for an animal. I think the zoo had one for elephants when I was a kid.
You're right, but that's a nothing hop for a kitty. Cats utilize vertical space more than we do usually. It's one reason they get more exercise indoors than dogs can. Unless she's disabled, in which case by all means accommodate.
There really is no need as she could simply walk around it without any inconvenience (the grille isn't as wide as the doors). She just prefers hop over it.
I’m basically Pavlov-conditioned to upvote the word “Miez” now. They could just post a text post with only the words “Miez cat good” and I’d upvote it instantly.