You can see just fine out of Metro North windows, which are apparently the same half-inch of polycarbonate glazing. So what’s the difference? Does Metro North replace the windows more frequently?
Likely due to less sun exposure -- either at their train yards, or the orientation of their lines being more north/south than east/west.
Also, Metro-North's two west-of-Hudson lines (which are co-branded/shared with NJ Transit, in terms of tracks and rolling stock) do have this same problem.