Ken,
On the debit card approval. The store has to run a settlement on their machine and that turns in to their bank what to request payment from your bank. Our machine at work runs the settlment for the days activities every night automatically, but I think some machines you have tell it to settle.
I've had about 4 debit card transactions never go through. I'm guessing the machine never settled and the businesses lost the info on the transactions. It amounts to about $70 worth of purchases over about 5 years. Two times at the movie theatre one at Wal-Mart of all places, a restaurant and somewhere else I think.
The only thing instant on the debit card purchase is when they run the card, the machine is just asking if your account is in good standing from the reporting agencies. The idea originally was if you tried to pay with debit card and you didn't have the money in your account it would be declined, but you can still overdraft with a debit card for the reason I listed above.
Now, if you buy gas at the pump the credit card machine "reserves" or "pre-approves" usually a minimum of $50 some max at $100. Even if you just buy $5.00 of gas, until the machine settles it still has reserved the $50. If you are that close to being over drafted and you buy something else later that day, you can over draft depending on who's machine settles first or contacts your bank first.
My wifes work issues payment cards if you don't have direct deposit. People were using those to buy gas and with the reserve and being a different kind of card, like a gift card sort of, they would try to buy groceries and the store would say they didn't have enough left on the card to pay, it was really there, but the gas station had reserved way more than they bought. Nothing they can do about it other than going to an ATM and withdrawing all they can in whole dollars and paying everything in cash. The kicker, if they take the cash out they are charged a fee by the bank ATM... they pretty much lose either way for not having a bank account to do direct deposit. The losers can't get a bank account because of leins and such will take the money from their bank. One girl doesn't get a tax return because of defaulting on student loans. My wife works with a bunch of losers and the good workers usually end up paying for their shortcomings.
I guess that was my rant...
