Talk:2335: Photo Deposit
Depositing cash through a smartphone app was one of the silliest and most useful features in GTA V. Unfortunately, depositing money would not duplicate it. Presumably the characters in the game are very honest and trustworthy, destroying any cash instantly after scanning it in. This honesty is to be expected from thieving killers such as these.
You can also withdraw cash via the app. How that works is beyond me.