Are the inspections to blame?
None of us can possibly know whether they are or whether they aren't.
Modern fairground rides often involve some serious engineering. Hurling a heavy car around gravity-defying tracks, or on hydraulically powered lifting arms is inevitably going to lead to occasional failures. If that happens when the car is packed with people there is a potential for serious injury or worse.
I doubt that there's a fool-proof method of preventing all fairground accidents.