I tend to agree, I don’t buy anything at the stations I use now because what I buy is available close by for a better price, the quality is dreadful at those pumpkin and upper crust places and I’d just rather pack something from home.
As for onboard, choice is abysmal on XC, quality likewise and availability is very unpredictable. By that I mean the trolley is now often only available in half of the train and you hear constant announcements apologising to the customers in the front portion of the train, catering is today only available in the rear portion (probably followed by an incomprehensible explanation that coaches G H L and Z might get a trolley from Derby if they’re lucky).
If we can’t expect or guarantee it is going to be there why should we not bring our own and just assume it won’t be available. At this point, price isn’t really a factor as we’ve all given up on it anyway.
Having said all that, I was promised chilled beers from the trolley on a very hot day recently, so I took the bait. Ordered my drink, watched the catering chap remove the lid and tapped my card. Only then did I pick up the bottle from the table and find it was definitely not chilled. It felt more like it had been sat on a heater all day. I don’t mind paying a little extra for the convenience, but things like this are what make it a rip off… a complete lack of quality product.