I think we might be talking at cross purposes. Car tax in the UK is to do with the emissions your vehicle makes and therefore contributes to pollution. In other words, you have to pay for damaging the environment.
Money is allocated from the tax we all pay to infrastructure. We all pay because we all benefit. So arguably, if you are paying tax then you are contributing to the upkeep of roads, pavements etc so asking cyclist to contribute to emissions tax is illogical as there are no emissions from a cycle.
I was thinking about this thread and chatting about it with Mr Scandi. I think the problem is that there are so few incidents with cyclists that when we do see something or experience something we are really shocked. I nearly killed a cyclist who went straight down the slip road of the motorway and out in front of me without stopping. I was doing 70mph at the time but luckily there was nothing in the other lane so I was able to avoid him. This happened shortly after my test. It has stayed with me for 20 years. However, I had forgotten about the lunatic in a car who overtook on a blind bend. If I hadn't swerved onto the verge, he would have hit me head on and I probably wouldn't be alive to write this. As I write, more and more incidents are coming back to me.
The way I see it is that idiots use all kinds of transport but we can't lock them up until injury is caused and by then it's usually too late!