Unfortunately, the UK seems almost incapable of building usable cycle infrastructure (possibly excepting London). Your idea is just a recipe for magic protective paint and even more abuse of cyclists who don't want to be forced to use ridiculously badly designed infrastructure. e.g. Here in Bristol, we have an infamous shared cycle/pedestrian pavement along Coronation Rd that has a few trees completely blocking the cycle side which just means conflict between pedestrians and cyclists who have to fight over the scraps left over from motorists taking most of the space (https://www.google.com/maps/@51.4462522,-2.6064792,3a,75y,80...).