While I try to never leave uninstalled material on an unsecured jobsite, my position is that any material delivered, and especially installed, belongs to the customer. They are the victims of the theft, not me.
Now, I don't claim to know the legal aspects of my position, but it is definitely where I'd stand. Now, for tools, that's totally on me to keep them secured onsite, and taken home at the end of the day.
