I don't agree with the suggestion that noticing or commenting on coffee spending is gendered or ageist. Coffee consumption is unisex and it's its daily nature that makes it seem small but add up to something big. Drinks in pubs and bars are expensive but occasional and a more obvious treat, not (for many people) just a part of getting through every working day.
There was a thread on here a few years ago that stuck in my mind, where a SAHM was trying to get through to her otherwise bright and capable husband that his daily cafe coffee and slice of cake added up to £thousands a year that they couldn't afford. He just couldn't grasp that 'one little slice of cake' that he felt he deserved, as a high-earning, successful man, could possibly be unaffordable to him.
The only example I remember being commented on, in my own office life, was the young man, not well paid, who bought fancy sandwiches from the deli every day, just for convenience, while supposedly saving every penny to go travelling. Older members of staff, who'd gone through the frugal years of life, were quietly incredulous about that (in a semi-maternal / avuncular way, so patronising and ageist perhaps but very kindly meant).
IME it's one of those things many of us do in our 20s when we feel richer than we are, feel we're on an upward trajectory careerwise and are happy to spend all our disposable income, rather than saving for the future. It takes a very sensible mid-20-something to think about future housing, childcare and recognise the potential costs of being a SAHP.
Which is fine if it's one of your chosen treats. It's when you want every treat, then the career doesn't progress upwards in step with aspirations and spending, that it all goes wrong. That's my concern about OP's DD thinking that it's 'normal' for everyone to have all the treats - therefore not seeing them as treats at all.