In principle you are right, but precision is an issue: the train control system needs to know the position in the centimeter range. Counting wheel revolutions i

In principle you are right, but precision is an issue: the train control system needs to know the position in the centimeter range. Counting wheel revolutions is notoriously unprecise because as the wheels wear down, they rotate faster. Public transportation is furthermore not an area of "hey I know, I just ask on Stackoverflow for an algorithm that counteracts the wear on the wheels". They do extremely conservative and defensive programming there (I once upon a time read the source code of one of the leading ETCS systems) in extremely restricted and conservative hardware (embedded 8080's in the 2000's) where the production process is audited and nailed down for everything (CF cards costing hundreds of $ for 128MB). Absolutely nothing is trivial there - the usual answer for an improvement idea would be a resounding "no way!". They are mortally afraid of the law of unintended consequences there.