A rate table is a snapshot of what institutions are publishing to everybody at once. That makes it useful for seeing the shape of a market on a given day - how wide the spread between providers is, where a category sits relative to others, which direction things have moved. It is not a quote, and it was never addressed to any particular person.
The gap between the two is not small. Reserve Bank research on the distribution of mortgage rates put it directly: advertised standard variable rates are indicative and are unlikely to be the rate actually paid on a loan, and very few borrowers pay the relevant advertised rate at all. Discounts vary with the characteristics of the borrower and of the loan, they vary between institutions, and they vary over time.
What decides an individual rate happens away from the table. Reserve Bank analysis of the recent tightening describes existing borrowers seeking a lower rate by negotiating with their current lender or refinancing elsewhere, and describes the discounts offered against advertised rates widening and then narrowing again as competition changed. None of that movement is visible in an advertised figure, which is why the average rate across loans already outstanding is published as a separate series from the advertised one.
The same distinction runs through the deposit side, where a published figure can be conditional or introductory rather than negotiated. Each category page here explains the mechanism for its own product, because the reason an advertised number and a received number differ is not the same reason twice.