When I come up on a stranded rig I willingly wait patiently until they ask for assistance. That way it was their idea. I also let them connect the tow strap. I'll inspect the connection but its all on them. They got stuck, they asked for help, they connected to my rig they told me to pull. That way it's all on them in a nice and pleasant way. What every you do do not ask for payment. The law says you need a license and insurance for that.
All good points. I ALWAYS make the other person hook to their vehicle.