[Jakob]

Amazon Prime is a good counter-example that delivery does not need to be subsidised as the pro rata delivery cost decreases if

1. more people order, or

2. people order more items

Both, 1 and 2 can be influenced by marketing and delivery can become a revenue instead of a cost center.

Bonus points if that means that you can deliver from a cheap warehouse instead of an expensive supermarket.

[michaelt]

Prime delivery is subsidised by the margin on the goods, how else would 'free delivery' get paid for?

[Jakob]

Delivery cost increases logarithmically (one package more in the same truck) while revenue increases linearly when more people order / people order more. Increase in revenue outpaces delivery cost even for low margin items.

Amazon makes more money with people on Prime, not less.