Markets, buyers & sellers, goods & services, and overall effectiveness
Markets do well with simple, uniform goods, with clearly-determinable, rapidly-ascertained effects, where buyers and sellers are each plentiful, the direct beneficiary, payor, and buy-side decisionmaker roles combined, the direct providor, payee, and sell-side decisionmaker roles combined, where individual recipient and contributor value is independent of systemic or environmental circumstances and factors, and external costs and benefits minimised.
Start relaxing or reversing any or multiple of those conditions and the market transactional fit wears exceeding poorly.
Adapted from a comment on @Joerg Fliege's post here.
