I'm surprised you don't know any inefficient people! I know many. A friend drives 15 minutes out of the way because that grocery store is a little less crowded (they're the same chain). They've probably been doing it for a decade.
> that F150 going 5 extra miles is more efficient than a Prius driving 25 miles from a Costco to their home.
but that's not what's happening, Amazon isn't driving a Prius to your individual home then back to the warehouse... it's driving to a hundred people on an algorithmically optimized route. They do this because efficiency at scale makes them more profit.
Individual people make inefficient preferential decisions all the time, because the incentive to measure and improve these things is too low to bother on an individual scale.
The human driving to work, various activities, to the grocery store (and wherever else) isn't doing it for just one item like Amazon though.
The vast majority of those Amazon packages are for one thing. When the inefficient pickup truck comes back with a whole weeks worth of $200+ groceries, that further increases the efficiency of the home buyer.
It's unlikely that a daily commuter would go to Costco for just one gallon of milk or a few batteries. But I know from my Amazon deliveries that single items are delivered all the time.
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Anyone grabbing just some extra milk or toothpaste is likely grabbing it at an even more convenient store, like 7-11 (mostly because you can't buy one toothpaste at Costco lol).