Suppose you wanted to build a new building for your business. You'd check the zoning laws, apply for the proper permits and hire a licensed contractor to do the work. These laws are intended to protect you and others from shoddy work that can lower the value of your new facility.
It works pretty much the same in Mexico, but Walmart understood that putting some money in the right people's pockets could bypass local and U.S. laws to get the job done exclusively and cheaper.
ATT tried the same thing in Illinois and drug companies do the same to doctors.
Money makes the world go 'round, but it takes scams to move that cash from your pocket into those who wield more power.