I’m so sad this has happened but I’m not surprised at all. Single bars which go over multiple of different heights, shapes and weights should be BANNED. I think they will be eventually, only after a few more deaths though. 

when DS2 was about 8 or 9 we went on the pirate ship at Drayton manor I think t was. He was over the height restriction but skinny and much shorter than the largest woman in the row. The bar came down and I remember thinking that it was only just tight enough for me never mind DS so we’d better lift it up again and bring it lower but it was locked and I couldn’t move it and thena second later the ride started.
Gradually, DS kept slipping down the seat next to me, he just couldnt keep upright from the momentum. He was terrified and I was trying to pull him up and he was sliding more and more under the bar. He couldn’t seem to use his feet to push himself back into position either.
DH and DS1 were behind us and I was turning to them saying “DS2 is sliding, he is going to slide under the bar and fall out” and bloody DH LAUGHED at me and paid no attention and was just enjoying himself with DS1
. He just didn’t believe that the safety bar wouldn’t be anything other than unsafe.
The ride attendant must have been paying no attention as they should have seen me trying to drag him back upright in the seat. But the ride went on.
Finally it stopped before DS had slipped right under the bar. We got off, legs like jelly. I was in complete shock. I had had images of him falling out into the lake next to the ride. Awful. I nearly vomited wirh shock and fear and just wanted to get away from the ride so didn’t even think to tell the (young) attendant what had nearly happened. We just tried to forget about it for the rest of the day.
The problem with those bars is that once it locks at the height it locks at, you’ve had it, you can’t change it, unless you attract the attention of the attendant. And with the noise and excitement of others on the ride, they just don’t notice, see that the safety bars are all down (no matter how it fits people in the row) so assume all is ok and then start the ride.
I really hope this didn’t happen here, it is a major design fault of these rides not to take into consideration that the safety bar will need to be at different heights depending on people’a stomachs and thighs.