>By operators exploiting themselves because of only coarsely tracked costs and low level of reserves.

Let's also not ignore outright gang/mob style affiliation of minibus transit organisations that will then also actively sabotage government public transport on their post profitable routes.

These private entities in the third world fill a role, but often are also rent-seeking and carve it out for themselves from a government without the willpower to A) build proper public transit infrastructure and B) defend it from bad actors.