no because it is not required.
Firstly, it's not a joint and it isn't a weld. So what are you going to NDT exactly? It literally looks like the plate steel sheared completely through where the seat support arm is. If there weren't any visual indications (and if you could actually see the area properly) like cracking in the paint or other distortions in the surface, you wouldn't be able to tell that was going to happen during routine checks and there would be no reason to perform testing on the area.
If it's not listed as an area of high stress, if it's not previously listed as an area of failure or fatigue, you can't just randomly go and NDT every entire surface of a ride. Aside from being impractical and just outright expensive, what about the time it takes? The ride wouldn't b able to operate with it closed so often.
As sad as it is, looking back through history of engineering (and not just amusement rides), a great deal of previously undetected failures in design or underlying metallurgy issues were found and corrected only when a failure occurred. Sometimes all the best math just can't account for the unexpected. Things like water ingress for example wreak havoc with structural components and often there is no sign anything is wrong until physical signs of fatigue present.
People who fly off the handle and blame manufacturers digging up "documents" that they either don't understand, or don't care to read are the same sort of people that fueled the fires when the terrible accident happened at dreamworld. Everyone on parkz hated that kind of coverage and blame game, especially when there was so much completely incorrect and misleading "fact" reporting, but now it's happening on the other side of the world it's ok? You guys are a bunch of hypocrites.
Wait until more information is made available and another statement is released from the ride manufacturer and don't jump to completely incorrect conclusions. It only makes the whole tragedy much worse.