I also don't beleive it would have made any difference whether she had a child or adult lifejacket on. The report is a little misleading when it says it was 3 times the usual buoyancy - presumably comparing a 150N lifejacket with a 50N buoyancy aid?
What she probably wasn't told was how to deflate
her lifejacket. For anyone that doesn't know, there's usually a non-return valve on the oral inflation tube. Turn over the cap and press on to the valve to release. Obviously critical information if you're trapped under a boat.
While you're getting ready for the season, now is a good time to check your own lifejackets. There's a good guide here
. The only thing I would add is not to test inflate by mouth but use a manual pump to avoid moisture/bacteria getting into the bladder. Leave it up for 24 hours to be sure.
I think that crotch straps will become standard equipment on lifejackets soon - was the case with ours from last year. I'm sure manufacturers would be delighted if crotch straps, sprayhoods and lights were legal/standards requirements. While it's down to the boater's pocket, sprayhoods certainly seem to be a low priority.