This is more of an issue with instacart. The vast majority of online groceries in the U.K. are served from supermarkets by supermarkets and the fulfilment rate

This is more of an issue with instacart. The vast majority of online groceries in the U.K. are served from supermarkets by supermarkets and the fulfilment rate is 95%+ with decent substitutions (typically a free upgrade to a more ‘premium’ product that you can decline at the doorstep)