Modern governments run many monopsonies, sectors where they are the only buyers. Spacex is selling to such a monopsony, for example. It seems that there, a simple change from cost-plus to fixed-quote pricing system made a huge difference.
A bigger example is roads, comm cables and a lot of "infrastructure" generally. These are sectors with a centralize core, and less centralized layers above it. Generally, the centralized layer is publicly run, contracted or highly regulated. Lending/money markets are a big example. Central banks at the core, large banks in the next layer, consumer financial services above that.
This sounds like an example of a centralized-core market.
There are just tons of example of things I would class as designed markets. Private companies can design/control markets too, the app stores are an example. The difference between a well designed/managed market and a badly designed one is huge.
In this example, how does it work? You need (or at least, they opted for) a centralised core: the part that keeps track of users, balances and allows transactions to happen. If there is to be a layer built onto this core, it needs to be well designed and designed for openness. We also can't expect competition or market forces to fix problems with the central core, at least unless that competition can be designed in.
We're really bad at this. Governments today do a lot of this, it's a core instrument. The difference between being good or bad at this is tremendous. One way or another, it'll need to improve.