Insurance companies aren't stupid. Why do they put up with it? They could e.g. force hospitals to publish pricing information so that it becomes common knowled

Insurance companies aren't stupid. Why do they put up with it? They could e.g. force hospitals to publish pricing information so that it becomes common knowledge and a market is created with accurate pricing. Or offer to replace overpriced medical supplies used by doctors on their own, which they acquire separately from the manufacturer and in bulk. Or - worst-case - start buying hospital stock at up to 2x market value so the profits accrue to them, and use investor pressure to start replacing hospital administrators with their own efficient bean counters. These are public companies, if they could get that 3% quarterly growth cutting costs from somebody "milking" them, why isn't that priority #1?