I'm sorry, but honestly... your post is completely superfluous. Nothing that you've mentioned here really even deals with Amazon's ethics.
#1 is purely based on the nature of their business in that they are an online distribution service. At best, this point may show that Wal-Mart does more good for the nation in regard to providing more employment opportunities.
This is the issue about how society has an interest in people being employed that can conflict with efficiency.
Is it always better to have an item sent to a local store and sold?
The bad news is, that wastes the resources of a building, the real estate it's on, the people who stock the shelf and sell the item and other things at the store, the gas and pollution and time driving to the store, the parking space and traffic congestion, the energy for the store...
The 'good' news is, it puts money in the local real estate market, employs people, and otherwise generates economic activity locally.
Consider three models to make the point:
Model 1 (Amazon): Internet seller - warehouses, delivery services, online, 1k employees
Model 2 (Retail): Sales same goods, local stores, 10k employees
Model 3: Sales same goods, Internet model, 1K for sales, 9K paid to dig and fill holes
The point here is that the third model might get the same thing done as theother models, and 'maintain employment' by pointless paying 9k people to do useless things 'just to keep employment' - it's waste. Sometimes that happens, when efficiency means those people aren't needed for the business. Thing is, that's 9k people who lose employment - and society has an issue with that.
In earlier times, 'there was always new business'. Still the case, in the global workforce?
Have we as a society come up with a political way of addressing this? One option being a safety net? Not really, we haven't. The policies are incomplete and under attack.
Retail having more hiring has some societal benefit - but isn't it sometimes no different than model 3 above, kind of useless?
When there are unnecessary less efficient things like excessive retail, is that all that different from having a better safety net and the more efficient business?
We count on the private market to use the resources for useful things. It doesn't always.
I think a useful idea is to imagine that 2% of the people can meet all their needs for food, transportation, entertainment, whatever - and the other 98% are not needed.
What do you do with them? What if the concentration of wealth is such that the 2% own everything - how do the 98% have land, food?
I think the idea here is to remind people to think of 'the good of society' and not only 'what's most efficient' because 'what's most efficient' might not meet a lot of needs.
Efficiency is good, but more is needed. There are issues you get into trying to compare the 'issues' with Amazon needing fewer employees, the good and bad for society.
That's not really much of an ethical issue for Amazon. It's more one for society.
What we need to do though it to not let the mega corporations take control of the government and set policies only for their needs, and leave the people without power.