are formal and informal institutions that SUPPORTS corruption. Sadly, the informal institutions that support corruption are buried deep inside our SOCIETY .
Im not saying corruption is right, it is a harmfull thing to society as a WHOLE. Im saying that wether we like it or not, it's a generalized practice in Mexico. The "mordida" is a clear PHENOMENA that pictures how mexicans in general see institutions, laws and how they make ilegal agreements between individuals. As this practices are so common NOWADAYS I would go as far as to call it a cultural thing.

Sure, you might not do it, and many mexicans might not do it. But culture is the believes and practices of the majority of the individuals in certain group, not of the exceptional cases.

Also about why Mexico has poverty. It's not only due to corruption or politicians. Look at history in 1920 when industrialization was a norm Mexico was a bleak moor. We have been behind the wealth race for centhuries due to many internal confilcts all trough XIX centhury and up until the revolution in 1920.