>And all buyers always have a "pre approved loan" (which is binding from the bank, they can't reneg it).

Yes they can. I've never seen one of those "pre-approved" loans that was actually contractual. All they really mean is, based on the numbers you've provided, the bank thinks you can afford a house that costs X. That's to keep people who don't have enough income from wasting everyone's time. But it doesn't put them on the hook for actually providing the loan.