The problem we solve
The check arrives. $247 for seven people. Three shared appetizers. One person had water. Another got the lobster. And someone has to figure out who owes what before the waiter comes back.
This isn't a "track expenses over time" problem. This is a "calculate seven different totals in the next 90 seconds" problem.
Here's the thing: the check already knows who ordered what. Every line item is right there. The $24 salmon. The $3.50 Diet Coke. The $5 fries with the +$2 bacon. The 8.875% tax. It's all printed.
Now your phone can read it too.