Here is an interesting and well-written analysis of a California case where homeowners face liability for the death of a tree trimmer they hired, because the applicable law considered them to be his employer. What I find almost as unusual as the story is the fact that the author is a professor and he writes so well.
When I was covering the crime beat for The Phoenix Gazette in years past, I heard of a lot of tree trimmer deaths. The typical scenario was an ex-con either went to work for himself or a landscaping service, went up in a palm tree to trim it with a chain saw, and the heavy fronds collapsed on him, crushed him against the trunk and suffocated him. I never heard of a lawsuit over these deaths, but that doesn’t necessarily mean there weren’t any.