Kids trikes and scooters aren't really road going vehicles so no, and for the sake of this argument, because they p*ss me off too yes bikes should pay road tax if used on the road I don't much care about the environment, that's not the point. A horsebox wouldn't cause as much congestion as it wouldn't be going anywhere near as slow, and you don't have to tip-toe round them. Maybe we (the motorist - your mother) should only have to pay tax for the miles we use our cars, I think binning road tax and putting the duty on fuel instead would be a much better idea but that's not the case. I have to pay tax all year round when I only do about 5000miles a year. If I wanted to drive my car a mile up the road it would still have to be taxed, so why shouldn't the same apply to horses? And I don't give a shit (no pun intended) how clean horse crap is, it's still unpleasant and potentially dangerous!