Why don't they have Jeep Grand Cherokee or Dodge Durango police cruisers?

They have Ford Explorer and Chevy Tahoe cruisers but no Grand Cherokee or Durango cruisers.

The Grand Cherokee and Durango twins with the Hemi V8 both make far more power than the Explorer and a little more than the Tahoe

They are also far more capable than the Explorer in terms of off-road capabilities and most likely handle better in high speed maneuvers compared to the Tahoe.

The Grand Cherokee would probably make an great police SUV, much better than the FWD biased Explorer and the truck-like Tahoe yet I have not seen a single one in existence. Why?

They may one day. Companies bid for the police vehicle contracts.

Not enough bribe money.