This is the fractional reserve system. The banks only ever have a fraction of all their account balances in reserve, and why a "bank run" is possible; too many people trying to withdraw their money all at once can cause the bank to collapse as it quickly runs out of reserves.
Thank you so much for this information. I realized now that it might be the main reason why you can't just withdraw as much as you can on a certain bank(I am referring to the maximum cash withdrawal per day). Because they were trying to protect a possible bank run. I can now differ to a bank's capabilities on how much their reserves are performing the higher the maximum with per day the higher the reserved that they have.
I think a possible bank run will never happen in the Philippine banks. Because aside from having a maximum daily withdrawal on the atm machines. The slower services will affect the total number of people who can withdraw during that day period