@starrynight - While you may not like the current system there is a good reason for doing it this way.
Banking transactions aren't instantaneous most of the time. When they are initiated, they show as pending. When they are completed then they are added or subtracted from your account balance. It's a good idea not subtract or add the money to the account until the transaction is completed, because not all initiated transaction complete.
I think if you just look at your statement carefully you can avoid overdrawing your account.