Because they have to manually install the program in each unit.
some service changes, like the M on CPW, are so rare, what’s the point of having to reprogram ENY’s entire roster for a reroute that’s only going to be used for a few days?
I mean, they knew about the 2010 changes months ahead of time, and yet most of the NTTs ran announcements and finds off for the first few weeks until their inspection turns came up, after the changes went into effect.