Umm, have you ever heard of the word 'diversification'? That's what cartels did, and now they control other illegal industries such as prostitution, immigrant smuggling, fuel theft, but also they are expanding onto legal businesses such as tourism, entertainment, food distribution, rehab centers, restaurants, etc. And all that shit is to launder the illegal money they make with the black ops.

I wonder if the drug cartels would rather go to literal war with the USA or have a legal market and keep out of the USA's hair.

The USA has infiltrated some cartels and instead, this resulted in the cartels fighting each other for control on both sides of the border. Is not as easy as you think.