Regarding food, I beg to differ. The top 3 grocers have price-fixed bread [1] (one prosecution since that article), wage-fixed [2] and have no-compete agreements for certain times of the year [3]. Food prices are not driven by underlying costs here.
1. https://www.cbc.ca/news/business/bread-price-fixing-loblaw-1... 2. https://financialpost.com/news/economy/how-hero-pay-scandal-... 3. https://www.cochranetimespost.ca/opinion/columnists/charlebo...