I have personally experienced situations like this on numerous occasions with mimimal set ups for out of the way, in no bodies way, on location photography. The park police at the end of this video were very nice but to perfectly honest that is not the norm.
I can see requiring forms, needing insurance, having permission via permits if people taking pictures showed up with trialers of gear to produce a Hollywood production, but a few people, bothering no one, photographing AND protecting nature and the rights of others, should just be left alone. Common sense on the part of park police should be the rule of the day. Is that asking too much?
And by the way why should someone with a phone with a camera not be subject to the same park rules as a person with a Dslr or mirrorless, or view camera?