Who cares what the statute/ordinance blah blah blah says. It is all about being competent in your private affairs. Once you infringe on the 'rights' of another because of your stupidity or miss thought, I hope you can right your wrong.
You should not need anyone to tell you that anything in the back of your truck not safely strapped/tied/bolted whatever, is a danger to everyone else on the public roads. Everything thrown into the back of our trucks is safely at all times tied/strapped/bolted/cinched ect. It isn't hard to teach. It isn't hard to do.
As for the trimmers being locked into their racks, that is a safety device guy.
As for what gcbailey said about liability insurance: Do you even know what liability insurance is? It is a safety net for those that are incompetent. It is for those who will never care or take fault of their own. It is for those who will in the end pawn off their ineptness onto someone else for their wrongdoing. There is no such thing as an accident.