>What distinguishes cartels from roving bandits that pivot to stationary?

You're asking the wrong question, I think. The 64 trillion dollar question, IMO: "what allows market incumbents to remain stationary"

The 'blame', as ever, lies in human frailty. Avarice and greed. Alternatively, you could look at avarice and greed as malformed extensions of self-preservation instinct.

Bad actors are omnipresent and relying on market forces to expel them from markets is like trying to pray cancer away.