This was an open-door “Photography Tour” where the passengers wear both seat belts and 8-point harnesses so they can lean out for photos. The harnesses did include emergency knives for cutting the restraint but in the shock of the moment it’s hardly surprising they were unable to free themselves.
I have flow in helicopters and many different types of aircraft and also fly as a photographer from time to time. When the safety briefing is given I pay attention then orient myself as fast as possible to the aircraft, ie, seat belt harness release, etc. From experience 99% of the non aviation people I fly with pay ZERO attention to the briefings or safety. I have a feeling this was the situation, they are pumped to go flying and failed to realize the most important part of the flight was getting out of the aircraft, alive.