Firstly, I completely disagree with this notion that young adults should be cutting off in coffees and cocktails every so often so that they can buy more expensive stuff in the long run. If incurring in these small expenditures every once in a while derives enough value for you to feel that you are leading a satisfactory lifestyle and as a result make you steer away from the big, impulsive spends (such as cars and headphones), then why not spend the extra dollar on a coffee? Even if you it every single day, at the end of the month you'll only have spent 30$ extra. If you did that every day for 2 years, you'd still only have spent an extra 730$, which is way cheaper than buying a new car. The goal for young adults should be financial independence, not to be able to spend large amounts of money in dispensable goods.
Secondly, I don't see how the fact that the app "doesn’t connect to your bank account or show depressing red info graphics". After putting in so much effort in reducing my spending, why should I have to manually input every dollar I spend into the app?