I can vouch for the testing and safety overhead when compared to what the layman might imagine. A friend of mine designs the ticket barriers for the London Underground, among other customers, and the work that goes into ensuring the safety of those autonatic saloon-door style gates is enormous - you can just imagine what a poorly designed or faulty one might do to, I dont know, a pregnant person. It’s definitely a case of the 80:20 rule applying to the design vs the finessing and safety.