I found the Metra system to be quite unreliable on weekends when I used it. The excuse was always not enough horse-power. Ever hear of DMUs lads? The Spanish CAF Commuter ones operated in Ireland were doing 150 mile intercity runs for months and managed that much. Surely a double header or more can do a local service?
Commuting in Chicago:
Commuting in Ireland:
Granted the passenger capacity is different, but higher frequency should solve that one. The Chicago standard where I was, had a 6 car set, while the Irish one is 8 car.
Metra tends to run Amtrak leftovers [like a lot of commuter-lines in the states]. oh, and generally finds funding sources an issue as though Chicago area mass transit systems have one of the lowest [either Chicago or NYC has the lowest actually] public funding %'s, it's never enough. Chicago and NYC are both near the 50%s.
oh and you neglected to mention Irish appears to be single-decker and electric, whereas Chicago's Metra is double-decker and diesel. [based on the picture, the closer facsimile in Chicago area is the L, as that's single-deck and electric]. the diesel vs electric can be a big difference, as it can tend towards the difference between one engine doing all the work, and every car doubling as an engine.
