When I were a young copper, all shiny and new, there were two other hobbies at my nick , each with near identical MK2 Escorts. After a long night shift one of them stumbled out to the car park half asleep, and without realising it his keys opens and started the wrong escort. He got half way home before he noticed the stereo was different...

Car theft has always been about. At some periods in the 60s and 70s it was more rampant than the hot hatch theft craze of the early 90s. Manufacturers have never spent money on security unless they were forced to do so by legislation. It doesn't sell cars, doesn't make them money, so they don't like spending on it.