I am sure more than a few users in here who know me are unlikely to categorise

my interests as 'traditional'
I think the last time I had a flask anywhere I was at school which was some time in the 1970s.
Quite apart from that, if you read upthread, I already commented that I am one in a position of a reasonably well paid job and who once did secondary spend on the railway(s) but been pushed away from it because of that pricing. But I am not going to pay double, triple, the high street odds when by just crossing that high street I get a much better deal. I am the the consumer I have to pay. I am not talking a few pence of a few % here, it really is double, triple, or more.
In plain English - and this applies to at least 4 railways I can name - why am I going to pay £4.50 or more for some limited range of sandwiches, and just sandwiches, when about 200 m away there is a supermarket with a bigger choice of better sandwiches and get a quality drink ad a snack for less than £4 (and maybe even their loyalty card discount as well). Read any other item you like vice sandwiches.
And any family etc visitors with any sense will do the same, especially when for 3 of those 4 railways they more or less walk by the supermarket en route from the station car park if they came by car (which I suggest is likely).
If your argument is based on "we don't want enthusiasts" and "we want families with secondary spend" then please tell me how the present high prices are an attraction for families rather than a deterrent ? I am sure many other retail outlets would love to know your operating model on that one.