The utility rate was not always fixed/negotiated: there's at least one utility company (Griddy) had an arrangement to pass-through market rate + small premium. Before the storm, this mostly meant getting rates modestly lower than the competition. The same customers were exposed to the power market spikes and received bills over $10,000. IIRC, Griddy has since filed for bankruptcy as the Texas legislature was generally supportive of individual customers not paying their bills. Paradoxically, Texas's political leadership allowed the utility companies to recover their losses by billing customers over years, which seems mostly performative/hiding expense from customers, but still decoupled from market forces.