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.
I know OP said they would go talk to their neighbor but I just wanted to add an anecdote. I worked at a place that had a bunch of trailers, and it wasn’t uncommon for someone to need a vehicle and just leave the trailer in the parking lot. One time someone didn’t secure it and it started to roll. A new guy who was trying to be the hero went to stop it and got his thumb crushed between the trailer and a steel beam of a pavilion. He ended up loosing his thumb. So yeah, chock your trailers and don’t try to catch a run away one.
Once tried to stop a small aircraft from rolling against a car. Upon impact the vibration in the wing knocked me over.
Next time I’ll let it crash and enjoy the show.
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.
losing a thumb is so bad, they do so much to help hold objects. RIP to that guys thumb