If people are knee deep in drug trade I don't think extortion comes into question. Like people said it's been carried out since the beginning. People from the mob have been involved in drugs since the 30s/40s but it was deemed immoral like theft. Personally I find it a wonder why extortion and kidnapping is seen as low of the low in Mexico but police corruption, rape and pedophilia go largely unnoticed
Mexico doesn't have a internet culture of pedophilia and it's pretty rare to find it, most of the distributors of pedophilia are from Europe and America. Rapes are actually lower in Mexico than America as much as 3 times lower. Though the stastistics could be higher due to low report though the cartels use rape as a weapon to terrorize and demoralize their victims. Also in some places like Sinaloa and other, the cartels routinely kill rapists and thieves. So there is a discouragement from society(the cartels) to rape. Police corruption has been seen as part of the system as long as Mexico has been "alive" so it's seen part as norm. Kidnapping has been in problem in Mexico for decades but it was mainly centered or done in Mexico city but then the cartels such as Los Zetas and others started to kidnap to fund their activities since they don't make as much money from drug trafficking to compared to others like Sinaloa.
