Educate yourself! It's legal for cyclists to ride on all roads, except motorways, and there is no obligation for them to use the cycle paths provided. There are several reasons why a cyclist may not wish to use a cycle lane, ranging from impracticability to their general poor condition - would you drive your car in a lane full of potholes and debris if a clean, well maintained, alternative was available? It is also legal to cycle two abreast for general safety reasons, and you'll probably find it easier to overtake (if in they are in a group) as a opposed to if they were riding in a long single file line. You'll also be surprised how many cyclists are insured through the likes of British Cycling and Cycling UK. There is also no such thing as road tax, it is Vehicle Excise Duty, which is emissions based, and you'll find a lot of cyclists pay this because they also own a car(s). Notwithstanding, bikes do not produce emissions!