I really want to just go put something under the wheels but I’ve never talked to these people.
Update edit: thank you for all the replies. I went over and knocked but no answer. It’s definitely not chocked. If I see them come home I’ll go back over. I’m worried as soon as the weight shifts loading it that it will just go down the hill.
If someone didn’t prevent their aircraft from moving they kind of deserve the expensive lesson. Aviation is about following procedures, and anyone who doesn’t follow procedures either needs a wake-up call or to leave the hobby/career. Those checklists are written in blood.