Agreed, but ...
The problem is that there are few common working practices between (for simplicity): ambulance, fire and police. As a consequence there is AFAIK no completely successful omnibus package in use in all three services in the UK. Each service has its own set of specialist software suppliers. It does not surprise me that a US system is having difficulties integrating with the Ambulance Service as well as UK supplied telecoms systems.
Curiously the Ambulance Service has the most to gain from computerisation because it has a fairly small, well defined, set of things it must do: take a call, send an ambulance, deal with the problem on arrival and either go to a hospital or back to a standby point. There is a simplish state machine and in a well run control centre, an average ambulance will need to resort to voice once or twice a day at most. The rest can all be done on a screen (or two) in the ambulance. Fire is more complex with computerisation mainly used for initial dispatch + job closedown but then anything could happen in between. Police is just "shout and holler" because they could be doing anything: there is frequently no fixed address to dispatch to, no-one knows what's going on (in any significant detail) and plod has to make his mind up when he gets there (wherever that turns out to be at the end of the car chase). You are comparing apples, potatoes and horse shit - not easy in the one computer system.
As for laying the blame in the right place, well Government is the agent of its own downfall by insisting on huge specifications and ITTs up front, spend years agreeing a contract, then the layers of contractors have to implement it (if they are all still in business waiting). Only problems? Well the spec was wrong in the first place because it was written by outside people, not consulting with the ambulance trusts adequately (or the contractors), time and tide has waited for no man and the trusts have so much more that needs to be done now anyway.
Remember: the number of distinct customers for emergency service software is very small, particularly if one specialises on one type of service. Most of the actual software houses are SMEs (usually SEs) and are sub-contracted through much bigger entities (for "safety" [of civil servants bottoms]). There could be two large organisations (with their markup) + the DoH between the SME and the Trust. There have been "consultants" involved as well. This is a long, stretchy and consequently very expensive piece of knicker elastic.
If Cameron were actually going to allow direct contact with the SMEs that physically do the work (and actually possess the domain knowledge), instead of merely talking about it, then it would all be much snappier and a whole lot cheaper.