For some reason I'm pretty sure the Army and Federal Police are running on 380MHz TETRA.
The corruption levels on the Army and Federal Police (PF) are among the lowest in the nation (and they are rotated often around the country), and that's why they are being quite effective on that task.
One issue that surfaced years ago was that drug cartels were getting radios programmed into the police frequencies and threatening them (and hearing them), of course, cities with high budgets (like San Pedro Garza Garcia, NL) had digital equipment and that rarely happened.
This is also a huge PR (like when the US helped Colombia in the 1990s), because with aid from Plan Merida, all of the money from purchases really goes back to the US (things like the Blackhawks), so you help the economy and get involved in a huge PR.
If the US government gives these radios to every agency or citizen in the country, then people would cry communism, but I guess in this case it's somewhat different.
And I'm not sure "what's wrong"with the current system, if I recall correctly, they run TETRA, or at least the PF does, so they're either getting new equipment to replace old/damaged ones, or, the army doesn't run TETRA and might get it (I won't be surprised if they do have some form of interoperability or mutual aid, since the Army does operate in conjunction with the PF sometimes).
And companies like GM make a lot of money from this too. They sell Silverados to the Army and Escalades to the cartels. Same with Ford, they sell F-150s to the PF and Mark LTs to the cartels.