Generally the ones that are on those plans are the most vulnerable. I've got a fixed TXU plan. The up front cost of being on it was a couple of hundred bucks because I had bad credit at the time. The pay as you go variable rate places don't have that up front cost and when it's not peak times they're significantly cheaper.
Unfortunately they don't always let people know in time when the rates spike. So these vulnerable people don't even realize they should be turning shit off or they're not home to do it or it's a heat wave/ice storm where they could just fucking die if they turn off climate control.
It's been a fucking mess down here in Houston. My electricity came up pretty quickly and I was able to head west and grab a hotel for a night so I didn't get heat stroke. I'm lucky. I was able to come back and eat the brisket I smoked before Beryl came through (I'm a stereotype, sue me). But there are people who still don't have electricity in this fucking weather and there are others who have to decide between their fridge and their AC.
I'm drunk, bitter, and pissed off tonight. So I'm gonna ramble.
Toss these guys a few bucks the next time your plan is up for renewal and see what rate you can get. Usually TXU is on the high side. https://www.texaspowerguide.com/