The problem with vegetation management (i.e. trees), is that both Railtrack and most local authorites are penny wise and pound foolish. The only things that get "cut-back" are the budgets to deal with trees until they grow so big they become an (expensive) nuisance.
Properly managed trees look really good, (whether prunded or pollarded, etc.), ones that are left to their own devices (at least those not growing in a park or the middle of a field), are a damn nuisance. Shrubs too benefit from being managed and it could be argued that they become more attractive to nesting birds in this case?
Next time you are driving along a tree-lined suburban road, have a look at how many trees have a "double-decker" shaped hole through the overhanging branches, its ridiculous.