There are some areas that have specific carve-outs to limit liability for inherently risky activities. For example agri-tourism in Oregon. If someone gets hurt or even killed on a hayride at a farm (eg), the farmer is not liable (with some exceptions). Hence when we go to a u-cut Christmas tree farm, they hand us and our kids saws, let us hop on a tractor trailer with them, and go chop a tree without signing anything.