The whole thread is a fun read. Some developer started collecting price historical data of goods on supermarker websites. Important context is that Austria has nutty inflation according to the thread author.
They see that different supermarkets change prices of given goods to the same level within at most a day of each other. This is probably because they are colluding.
Many goods are also on discount periodically and frequently. So if you buy this good weekly and there is a discount every other week, the real price you are paying for this good is an average of the non-discounted and discounted price. So supermarkets can ruse you by reducing the non-discounted price and increasing the discounted price making it look like they have reduced prices without not being any worse off.
There is also a bit about how Austrian products cost more in Austria than (say) in Germany.
Pretty insane. Always cool to see that in supermarket cultures there is zero consumer protection. I would say that basic necessities should come under planned economy but that would be communism.
It happens in North America as well. There was a news bit about how Canadian supermarket chains were colluding to price-fix bread.