Entirely correct. I'm from Western Europe, and almost everything (or at least a great lot) that is humanly accessible is meant to be used by humans, including grass. Note that this is not in opposition to "carefully manicured", as there is plenty of lawn (for example) which is carefully tended to, but still publicly accessible.
It's also totally natural to sit on art, if it's convenient for sitting, even if it's many centuries old.
A decade ago I moved to California, and it's a very stark contrast there. There is so much greenery and similar that is just "off limits" and made for just looking at it.
Generally, in California things feel much more "fenced off", even without any actual fences.