People don't realise how costly monopolies are. I work for a UK hospital, and have worked in the department that's responsible for purchasing all of the medicines the hospital uses. We have an online system that tells us for any given drug that generic A is the cheapest at £0.50 per box, generic B is £0.60, generic C is £1.00 per box and generic D is £5.00 per box. If every hospital buys generic A's levothyroxine, then generics B, C and D will just stop producing this medicine, because there's no market for it - and then if generic A wants to charge £20.00 per box, they can, because they have no competition to bring the prices down and the hospitals need to buy levothyroxine.
So instead, the hospitals are grouped into purchasing regions, and one region will buy generic A's levothyroxine, one will buy generic B, and one will buy generic C. (Generic D doesn't get a look-in because its prices are considered unreasonably high). The hospitals that were made to buy the more expensive levothyroxine will then be told to purchase the cheapest simvastatin, and the middling-cheapest flucloxacillin (while the people who bought the cheap levothyroxine will buy the more expensive flucloxacillin), so no region is out-of-pocket overall.
And yet, when I've mentioned this to people, they seem to think this is unnecessary, and all the hospitals should just buy the cheapest version of every medication. Here's what happens when a company is given a monopoly and decides not to play nicely with its customers: