So what you mean to say, with safety issue, is that government-provided infrastructure is so badly designed and ill-equipped to be used at the necessary scale attempts to improve matters must be stopped !
Yes, at peak times there is congestion (just like at peak times there's highway congestion), and the existing infrastructure (built mostly before 1930) was built to be significantly safer and more efficient than existing systems. And 90 years later, it still is usually the most efficient and safest mode of transport in NYC. But given the record number of subway riders and record age of the infrastructure, it takes everyone pitching in a little to not make the situation intolerable. Part of that "pitching in" is "Don't go onto the platform before the train's riders have left".