Corruption is like cancer. It spreads and metastasizes through society quickly. If students see other students cheat and get ahead and not get punished they'll be incentivized to cheat. If instructors see a large number of students getting 100%, obviously the material is too easy, they'll make the problems harder. Pretty soon it is impossible to operate or do anything without either bribing or cheating.

Dishonesty and a cavalier attitude towards cheating is something taught at home early on. Poverty, institutional disfunction play a role but at some point they become part of the societal mores. If you don't cheat you just look stupid and naive and people make fun of you.