Indicators on the Subway and Bus

Yesterday while riding the E train to Queens I noticed a sign that stated that the MTA is offering a service whereby it wants to send weekend subway closure advisories directly by email to your inbox so that you are always in the know about disruptions. While this is a step in the right direction I cant help but wonder why the MTA can't arrange to equip their subway stations and buses with electronic indicators that inform passengers about the arrival of the next train or bus. I have seen them in other cities like London and Singapore then why not in New York which has one of world's oldest and most extensive subway systems? Sure some of the stations have announcers who make periodic
announcements about the approach of a train but most times those announcements are so muffled that nobody has a clue about the status of the said train. Currently most commuters (including yours truly) track a delayed train by almost hanging over the platform and craning their necks in order to catch sight of the red light which indicates the approach of a train wouldn't an electronic indicator be a civilized solution to this problem?