What if they are not? If the loan isn't granted, then the lender will have to go elsewhere, and worse case they will have to sell the property, possibly at a loss. That would seem like it just exposes the bank to more risk? Situation here is that you simply keep paying and the bank doesn't care whether you pay 110% of your income because you are unemployed, or 10% of your income because you got promoted - so long as you are paying.

Stress tests/qualification can therefore be against a "high interest rate" which is typically 7-8%.

What's interesting is that even a 4% interest rate at this point would probably lead to a recession because people are so highly in debt that they would cut saving/spending immediately. That recession would likely see interest rates plummet again. So the "new equilibrium" is a scary low.