Holly, a beautiful calico kitty, was lost almost 200 miles away from home and yet she found her way home. Cats especially are good candidates for microchips since many of them "accidentally" lose their collars until the guardian gives up putting one. I recommend "Beastie Bands" since they are stretchy and soft but even with these some cats will try to get out of them and then be stuck with it around their chest and one arm out. Consider a snug fitting harness while traveling, certainly if you have to take them out of their carriers such as at an airport. Or better yet, hire a wonderful pet sitter so your cat can avoid the hassle and stress!
Being on the road as much as I am I see quite a few dogs loose in moving vehicles or sitting in the driver's or passenger's lap. It is illegal to drive with a dog in the open bed of a pickup truck but there are no companion animal restraint laws similar to laws for babies and children that I am aware of. I have heard of dogs being expelled from cars that are in accidents and either dying at the scene or being lost. Think about it - how would your dog (or cat, although I know anyone reading this is far too intelligent to let kitty ride loose in the car) survive being thrown around a vehicle if you were hit or simply had to slam on your brakes to avoid an accident? Every pet supply store sell restraints sized for individual dogs that attach to the car's seat belts or for small dogs, a carrier could be secured in the back seat. Many of us think of our animals as our "kids" but it would be unconscionable in this day and age for any parent to let their human child stand up in the back seat while the car was moving. (It was different back in the 1950s when my sister had her front teeth knocked out when mom had to hit the brakes hard.)
I will end this post on a positive note: I just today heard the happy ending to a lost dog story I was following. A senior dog was lost when his also senior guardian was rear-ended while driving his dogs to the vet in Kirkland. Paramedics had to access the car to get the man out, resulting in both dogs fleeing from the car. One dog was immediately caught but the other poor girl was lost for 11 days! Fortunately volunteers posted fliers throughout the surrounding neighborhoods and a kind person who had the dog in the backyard and had been feeding her saw the fliers. Yeah!