Right, so with Amazon you have one truck visiting 100 addresses every day for two weeks (because people are buying 2-3 items per order). With Costco you have 100 people each driving to Costco once, on a single day.

From a cars-on-the-road and fuel expenditure perspective, the latter sounds better.

If Amazon customers ordered like Costco shoppers, the Amazon model might very well be better. But they don't, so it isn't.

Right, 100 trucks delivering 100 single items to 100 homes, or 100 consumers each making 1 trip to buy 100 things. It really depends on the details too much to simplify it so far.

Amazon routinely is delivering things to my house 3+ times in a single day. They don’t do a great job of grouping their orders into deliveries.

We’re usually to “blame”. We don’t do coordinated orders in our household. We have 3 people ordering individually and I know I sometimes place multiple orders per day. But, I’d expect that shouldn’t matter and they’d notice all these orders with the same address could be put on the same delivery truck. Instead, it seems they just process orders as first in first out.

They have recently added a feature in the delivery options if I already have a pending delivery it will say “add to your Tuesday delivery” or similar, which I’m likely to choose. For a while they really wanted me to use an “Amazon day”, which would be like picking Tuesday as the day of the week my deliveries would come on. I specifically pay for Prime to have fast delivery so I don’t understand why they ever thought I’d go for that.