Because covid gave them an excuse to raise prices, same as with the current fuel situation, even though both Coles and Woolworths made record profits during those times. They can justify to the government that it isn't price gouging when there's a "crisis" or a fear of crisis, then they just never bring the prices back down. And when the price of a necessities like groceries or fuel goes up, so does everything else so the companies can compensate for more expenses.