Nothing wrong with buying over the internet, vast majority of customers get food with 2-3 days shelf life just same as in the shops, I still choose from the back of the shelves as that where the longest dates usually are.
The issue is with supply, for example bread wont be baked in store in time for a delivery before lunchtime, or the fruit n veg be at its optimum time because it has to be unloaded, checked and then fulfilled usually around 3am in the morning with limited staff.
Supermarkets on the whole are well prepared but there are some that to a certain extent got caught on the hop by competitors and as such as playing catch up with staffing levels, vehicles and infrastructure all of which costs money.
Most large supermarkets will make on average £1 profit from each delivery so is more of a good will service rather than a money making expertise.