“Am I considered paid worker or not?” asked Shimon. “Mr. Deckel didn’t pay me for helping me load the branches.”
“Although he didn’t pay you specifically for loading, since you gained through your work with the palm branches, it is considered pay,” replied Rabbi Dayan. “The pay doesn’t have to be direct pay; it can even be indirect benefit. Thus, Shimon is liable for the mirror if his actions caused the branch to fall off. A neighbor who helped for free, though, would not be liable if the owner also initially loaded the branches in an unstable manner.” (See Pischei Coshen, Sechirus 13:15.)
“The local custom [minhag hamedina] must also be considered,” concluded Rabbi Dayan. “In some places, the custom is that the seller is responsible for loading the branches on the roof, in which case he or his worker would certainly be liable. In other places the custom is that if a person wants to take the branches home on his own car he bears responsibility for any damage to the car. This has to be verified.”