Cycle Response Unit bikes- why are they so expensive?

It's a low cost way of getting around, however the cost of the slower transport in terms of person hours would mean that it isn't going to be a viable option.

I've toured on a hardtail with full panniers and it was a fairly enjoyable ride.

You kind of have to have a one size fits all approach because it needs to be deployed to any number of unknown scenarios. It needs to fulfill a remit that the cycle responder can attend quicker than a box ambulance, a car ambulance and a motorcycle first responder. It's about responding in close and complex urban environments with a risk of heavy and stationary traffic with sufficient supplies to be able to preserve life until a better medical function arrives.

Bumping up and down kerbs. Handling potholes, loose flagstones, steps and the occaisional bit of cross country in all weathers. A good carrying capacity for trawling lots of kit without shaking it around more than necessary. A bit of stability on those occaisions when you need to get off and push. Starting from that spec I would make a wide bar, trigger shift, broad geared, chunky road slick hardtail my first choice by a long mark.