Currently rather busy emptying the public coffers into the pockets of the banks. Unemployment is rising rather quickly so the tax haul is reducing - thus, a new income stream must be found and the internet is untaxed.
You could argue, and you'd be right if you did, that connection prices in the UK, as say compared to Europe, are extremely high with a seriously sh*tty service for your money and that this constitutes a form of tax. Call it a "ha ha, you live on an Island, where are you going to go for a cheaper connection?" tax *(the same principle can be applied to most things on the particular bit of dirt we call the UK).
It says everything you need to know about Government, the ISP's and capitalism in general. Profit is privatised and loss is socialised.
WIth a bit of luck it will be a voluntary tax and we can all refuse to pay it and f*ck the lot of them.