Well, given that the cartels probably don't have a lot of engineering and design talent on the payroll they probably did meet their design specs.
1. A vehicle large enough and fast enough to make trans Mexico drug runs.
2. Provide for many armed guards.
3. Armored to protect the guards and the contents.
4. Able to plow through roadblocks
5. Air Conditioned for comfort an a controlled environment for the drugs.
Not pretty, but does all of that.