But it would be collectively good for them, so if enough band together, they can lobby to put the practice into law in some way, or just the 3 biggest insurance

But it would be collectively good for them, so if enough band together, they can lobby to put the practice into law in some way, or just the 3 biggest insurance companies can agree between themselves to use that pricing scheme. I don't think that's the same as conspiring to keep prices high, which is usually looked down upon.