Are you saying using 1GB of data a day on a smartphone is normal for smartphone users? I have a 10GB plan not because I need it (looking at this year, 2GB would be more than sufficient) but because that’s about the lowest I can get nowadays.
Certainly if, as indicated, the intent is for these users to have a phone for essentials, not for watching YouTube or playing music, 3 GB, IMO, should be sufficient.