An interesting thing though. If the banks keep on increasing the interest rate above what the Reserve bank dictates, then that actually makes it less likely that the Reserve will need to raise rates so soon next time.
I suspect the banks have worked this out and have made a decision that the extra revenue might as well fall to the banks instead of the Reserve.
Of course, it would be difficult for the banks to raise interest unilaterally, so I think its a more convenient trigger to wait for a rise by the reserve. Then most of the 'blame' falls to the Reserve and falls away from the banks.

On the other hand, for investors is this such a bad thing… if the rates are higher then less home ownership, and more renters. Ultimately it could be better for first home buyers as well if the result is that house prices are contained by the higher interest rates… but no doubt quite a bit of pain now.

Just to put this in context though…. I recall when interest rates leaped to 17%. That was scary.