> I'm sure there are commercial (not even paid necessarily) apps that do all this, but this one is used only by us and it's built to perfectly interact with our lives
There is another factor you may not be aware of: shopping apps are juicy targets for acquisition by marketing/data mining company. I mean, there is no clearer indication of what you want to buy than what you put in your shopping list, so it's perfect source of data to mine.
Out of milk is such an example: it was a good app with 5 million users, then it got sold. Users became the subjects of data mining, or their account got deleted (if in Europe). Fun!
https://www.prnewswire.com/news-releases/inmarket-acquires-o...
https://twitter.com/JamesLiamCook/status/1407370148349198341