How about this one. Mr. or Mrs. or miss thief hops over fence and steals car or just car jacks someone whilst they're at a red light or stop sign. Will thumb prints stop that?
How about this, while car is sitting at store, movie's, whatever, thief steals car and brings it to a chop shop. Will thumb prints stop that?
Thumb prints are just another way to get the people used to the idea of being tracked and prepare them for the eventual bio-chip implant.
Nor will thumbprints stop lightning from hitting the car but that is as irrelevent as your comment. Thumbprints or some form of conclusive identification will be required by rental agencies should collossal loss rates due to theft by fraud mount. This is not a political issue merely an example of creative private property owners attempting to safeguard their property.