This happens everywhere in the country, not just Texas. I've got friends who work in several federal law enforcement agencies. Everyone loves a drug bust because your department gets money for toys, it's very quantifiable (we took X pounds of dope off the street, worth X number of dollars) and there's virtually no recourse.
You don't see it, but in every major metro area you have the police department, the sheriffs department, the state police, the DEA, DHS, ATF and FBI (at a minimum) all vying for big drug busts.
I understand that. It's not the same as the "catch & release" w/ forfeiture you describe earlier. It's not what NE & OK are whining about, either, which is very small quantities of retail cannabis transported into their states.
I also realize that the war on marijuana is half the war on drugs & that legalization threatens the gravy train you describe. It'd mean half the gravy won't be there any more, the easy half.
The rationale for outright prohibition of any drug is that use of it causes significant societal harm, that it damages people who use it & those around them, too. Such prohibition also has to apply to a relatively small subset of the population if the people are to support it. That's why alcohol & tobacco can't be outlawed, regardless of how harmful they might be.
Cannabis use never satisfied the first part of that. If it did, we'd have ample evidence of it considering widespread use since the 60's. It doesn't satisfy the second criteria, either, rendering enforcement a travesty against equal protection & the principles of Justice & public welfare underlying due process.
While the acquisition of goodies may be sufficient motivation for law enforcement agencies, it also promotes an unhealthy mercenary attitude. Why would they direct their efforts towards crimes of violence & fraud when other directions are more lucrative?
It also leads to a variety of perverse outcomes. Landlords lose their property because of actions taken by their tenants & lenders lose their collateral through forfeiture. People lose substantial sums of cash on the presumption that it's drug money.
Arguments that it helps to defray the cost of law enforcement fall flat in the face of such underlying injustice. It also promotes acquiescence to the police state since we're not paying for it.