I agree with you. Back then when they made the trading update in late 2018, the trading outlook definitely didn't look good with all the margin pressures and reduced consumer confidence and they just were honest with what they were seeing from their position at that time. That actually can be explained by the reduced sales growth rate which was 7% back then but only 3.1% at the end.
I am very interested in how the sales were made i.e. the growth in aus stores and online sales. Store traffic may have been much lower but there may have been a good increase in online sales where they benefited from investments in online platform.
In accounting principles, you should not overestimate your revenue/assets and underestimate costs/liabilities and the same should go for the management? (I am not sure if this prudence concept is still part of GAAP though!)