The UK police don't carry guns unless they are specially trained because it's too costly to train all the police officers in the UK for gun and taser use as well as the cost of the weapons, ammunition, and it's also due to public perception.
The reason most of the UK police don't carry tasers or guns is because they are not specially trained to handle the gun or tasers against assailants.
The UK does have specially trained police who do carry and have tasers and guns and only those police will use the tasers and guns when needed.
Every Police force also has a firearms unit, with armed response vehicles.
Since 2004, police forces have issued Tasers to Authorized Firearms Officers for use against armed assailants which are considered by the authorities to be a less-lethal alternative to conventional firearms.
Another reason most UK police don't carry guns or tasers is public perception.
The police in the UK come from a proud history and heritage of being largely unarmed.
The public like that and so do most cops.
The problem with a Taser (I’m referring to the X26 model here) still looks like a gun.
Yes, it's big, it's yellow, it's plastic but essentially it looks like a gun. It's gun shaped has sights on it and a trigger and it fires a projectile.
However, the rise in the terrorist threat and of violence against officers that perception is changing.
I've written about this on here before.
The public expect to be protected and expect the protectors to have the right tools and resources to do that.
The next is cost.
There are a number of elements to the cost side. It's not just a matter purchasing tens of thousands of Tasers, there's the cartridges, the spare DPM’s (essentially a battery unit that also stores data about the Taser’s usage, the lockers to store them, extra kit such as holsters for officers to carry them.
On top of that is the training.
The initial course is 2 days followed by a 1 day annual refresher.
And the sheer costs involved would be largely prohibitive given the current state of police budgets.