Most red drum tournaments are by length...that allows you to measure over slot fish then release. There are a few exceptions you see on tv sometimes, the ones that copy the bass weigh in format. Those are in the minority.
Also, worth mentioning this same thing happened (weights in fish) a few years ago on a pretty serious bass circuit, I think in Texas. Well documented many places, including here, I think. So no, this isn't just a walleye thing. Just one more reason I stopped tournament fishing.