ORCi tracks, some ORCi formulas and BriSCA formulas have invested heavily in AMB Systems since around 2004, the equipment is very expensive [but very good quality] for the promoter, and the transponders expensive for drivers, but its like money in the bank - the resale value of them is amazing and a driver starting in ministox etc can keep their Tx until they eventually leave Oval racing, and if they want to sell up sooner they will get a respectable amount back.
Now called just "MyLaps" the company have brought out a new type of Tx that does have GPS etc, I can see value in that for circuit racing and rallying, but not ovals.
The oval tracks use the system primarily as a secondary lap scoring system and not for timing, sure the drivers like the timing side of things to help develop their cars, perhaps cars have come on more in recent years due to that info being available to them, in a way perhaps it has made drivers think more about set up, and in turn spend more money to get that little bit quicker over their competitors in car development.
One thing that is overlooked by many, is that the system has to be portable, taken from track to track by its operators, this is one of the reasons that not many [if any?] UK tracks have MyLaps scoreboards.
And like everything computer related, transponders and equipment go wrong from time to time and that will happen with ANY timing system.