The problem is that the User Services (or to be more specific: the Home Office) seem to think that they need a "one thing does everything" approach (on Android), whilst ignoring the fact that most high bandwidth data doesn't use one's handheld TETRA radio. The little that does could be accommodated through one's smartphone over IP and, if you really must, through your own MVNO. You don't need to spend 100s of extra pounds on smart phone that do "press to talk" (badly, especially compared to Tetra).
But then TETRA (in the shape of Airwave) has always been looked down on by Government who have regarded it as too expensive. It was them that sold it off into the private sector in the first place. As a monopoly. Several times - just look at the list of previous "owners". Needless to say the Free Market has worked its magic and costs have risen well above inflation ever since. When ESN finally beds down into something useful, they will repeat the same mistakes all over again.
The Android thing they have is interesting, because they *still* appear to be under the delusion that they can buy an "off the shelf" app to do anything they want - like call and dispatch - which requires a whole raft of specialist, low volume, back end and operational programming to achieve. Just where are you going to get, for example, a police, fire or ambulance dispatch system from? The App Store?