Corruption is so widespread in low income markets because of the general lack of multinationals and lobbyist groups.
Most people simply don't have the ability to get abnormally rich by (otherwise legally) setting their own remuneration from the exec room of mammoth corporations, or getting juicy consulting fees by (again, legally) representing those.
They make up for this handicap by asking (and giving) bribe while in government employment. Thus, everyone else gets ripped off not as shareholder, but as taxpayer. The ones at the bottom of both pyramids get the worst deals.