Years ago, I used to work for a bank. If fact, a couple of them at different times. Lets say that bank is called "The Bank of LW."
As luck would have it, my own bank account was also "The Bank of LW"
If payday was on the 25th, then the money was always a day before. It showed up on the ATM, but not if you enquired with the bank teller.
If you were not with "The Bank of LW." then your money would not show up on the ATM the day before.
If the 25th was on say, Sunday, then the money would show up on Thurdsay (for me) and Friday for staff who didn't use the same bank.
In reality, the money is in the bank but won't show up. It's a sneaky way for banks to make more money.