As noted in the other answer the error is because you are trying to run a GUI app when not logged in.
However in your case why are you using a GUI app (Terminal ) here.
Just call your scripts directly from the cron script.
e.g. daily.sh should be
#!/bin/bash
~/backupThing1.sh
~/dailyThing2.sh
Note that you might need to have absolute paths not ~ here as cron jobs do not have the same environment as when run in the terminal.