Incorrect. There are a lot of choices for energy consumers in Texas.
There is one Grid Operator (ERCOT, a public/private entity) and one electricity delivery system (ONCOR), but consumers buy electricity in Texas from any of a number of energy retailers. The largest is probably TXU Energy. Each retailer is just a go between between ONCOR and the consumer and each has its own billing structure.
There was one company, Griddy, that basically charged consumers a monthly flat fee and then charged consumers whatever the instantaneous wholesale rate was. As such, there was no margin to mitigate the spikes and consumers simply couldn't afford $9,000/kW-hr, so the company went bankrupt. Under normal conditions Griddy was the best deal for consumers, but when the grid crashed and prices spiked the company had no way to mitigate that. They saw what was coming and begged their customers to switch, but the way the companies work you can't switch instantly Griddy was screwed. But that was only like 0.01% of customers in the state or something like that.
My company "overcharged" me enough that when things crashed they were able to eat the overages. And we never lost power.
(My friend who lives a mile away lost power for 4 days in subzero temps. His wife feeds a bunch of feral cats, so when cold snap hit they let the cats stay on their enclosed porch. They stayed in their house. Luckily they're avid campers and had good cold weather gear. The set up a tent in their living room and slept in it. I think it got down to about 30 degrees in their house.)