Demonstrates how difficult it is to have a "fair" capacity market. ERCOT so far has wisely avoided having one. If eventually ERCOT does establish a capacity market, for which there is pressure, it won't be bound by FERC rules as ERCOT is entirely within the state of Texas.
First notice the price pyramid. The least amount is for transmission, next for ancillary services. ERCOT doesn't have a capacity market, which is much simpler to administer.
Next note all the detailed components which go into stabilizing a grid, with then the pricing fairly determined, partially "by the market". I believe that the largest components are for up regulation, i.e., more power, and down regulation, also difficult for some types of generators to accomplish quickly. However, the reserve component is supposed to be around 13% of generation so there's a hefty payment to the generators in reserve status.
Then there are all the mini parts of grid stability.