I could be wrong but I would imagine there's simply too many intermediaries in today's world for this to happen as frequently as it used to. Since the 70s-80s when highjacking was still a popular racket there's been a strengthening of state police in most places as well and more cops in general be it state, highway, or local patrolling the highways. Not to mention you're no longer ripping off just one trucking company, your'e ripping off a trucking company hired by a logistics firm who in turn was hired as a go-between for a 2nd trucking/distributing company. That accompanied by the new security measures in most trucks make this once popular racket a relic of a simpler time.

^^^feel free to correct me if I'm wrong, I've often wondered this question to myself and to the best of by researching ability this is what I've come up with