Having worked in Customer Relations for a former TOC myself, I always tried to tailor my reply whether by email or letter, to address the customer's specific point. Unfortunately this meant that the number of letters and emails I was sending out was much lower than my colleagues who just cut and pasted standard responses, which as you'd expect, my manager wasn't happy about. In the end of course, I just ended up using standard responses myself, only being more specific if the workload was lighter (it rarely was!).
I don't use twitter but I would imagine the vast majority of twits (or whatever they're called) that get sent are from people with nothing better to do just having a whinge, so I can fully understand why the overstressed rail staff sometimes resort to generic repetitive responses.