Can my dog ride in the back of my pickup truck?

California has the "tethered or crated" law. I can't count the number of times I've seen a dog with a rope tied around its neck and then tied to the back of the pickup. 98% of those pickups have plenty of room inside the cab for the dog. It makes me sick to see as a sudden stop could toss that dog over the side of the pickup and break its neck. But those folks "love" their dogs.