If I were King of Amazon for a day, I’d initiate a project that would help them aggregate deliveries.
Before I retired I worked in a different type of logistics and you can be sure that they working on this very hard.
The problem is that this things like this may have unintended consequences.
For example if they delay an order for say three days to consolidate orders then they would need to reserve that item for you on the warehouse shelf. That would increase their storage costs and their inventory costs. They could easily end up with millions of dollars in dead inventory sitting in a warehouse that is using up lots of warehouse space. In some cases they may even need a larger warehouse to hold that inventory.
In areas with high population it is likely that an Amazon truck will be going down your street at least once a say anyway so it is not like they could save a trip by consolidating orders.
What is best gets tricky.
I don’t recall seeing it recently but I recall seeing things like a $1 credit for digital downloads if you agreed to slower deliveries.
I have also seen them give you an option for slower deliveries about a week or so out if you did not need something soon.