Don't you think that the reason may be much more related to why mail-order went down before ? In other words: Amazon exploited a tax-loophole that could not be easily closed : the interstate commerce tax clause.
But create a trillion dollar companies by "stealing" taxes (as Jeff Bezos did), and states notice, and there's one thing that unites Republicans and Democrats, Obamas Bushes and Trumps, and it's green. To put it another way, people managed to untangle all the knots and ... it happened. Lots of laws got changed, but the real breakthrough was here:
https://techcrunch.com/2018/06/21/states-will-be-able-to-cha...
Bezos essentially gave Americans a tax loophole for goods ordering and made it work, and took ~18% of what he gave them for his company (and about 4% for himself). He now has a trillion dollars. Americans have lots of stuff delivered to them.
But now, Amazon has the same problem mail-order has had for a very long time: it's just not cheap anymore, and so they cheat, underdeliver and overcharge, just like mail order has to do. It's trying to fix this, but the truth is that home delivery is just a lot more expensive than stores, and there is no fix.
And surprise ! Walmart suddenly stopped losing against Amazon. Weird, no ? Well, no, not that weird at all.
Of course Amazon is constantly criticized for being an example of what's wrong with capitalism. Reality: government created Amazon through tax law. I'm not saying that's all there is to it, but it's close.
But yeah this is a silicon valley forum, and the idea that the founders of the US, and a good lawyer and a supreme court decision from 1992 were the real power behind one of the great silicon valley tech companies is just not going to be a great explanation in many people's opinions. Amazon just isn't a great technical accomplishment. It's an incredible financial engineering accomplishment.
Of course, this makes it very ironic that people like Bernie Sanders criticize Amazon, as Mr. Sanders is part of the institution that made it possible in the first place. If Bezos didn't build Amazon, someone else would have figured it out and built it (it took Bezos >6 years). However, if the Federal government would have taxed Amazon the way it taxes everything else, there would have been no Amazon. Any other companies that were created would never have been anywhere near the size Amazon grew to.
Note that the rise of China, the gearbest, jd, banggood ... rise is the result of a similar tax fuckup, this time at the united nations postal union. Or: China only works because they get to offload the cost of shipping on the taxpayers. And now Trump is
However, I strongly disagree with Trump's approach. I would prefer to see the opposite happen: that US companies get brought on a level playing field with China. If you can ship from Delaware to New York for 1.6$/kg, what would happen ? It'd be then end of Chinese exports to America, but without Americans having to give up what they gained in the past 10 years. I think there should be a lesson for our government in here. Namely, that financing the post office was one of the best decisions ever made in government, and that we should look into having 50% or so of the cost of shipping paid by the (ideally Federal) taxpayer, not just when shipping from China. Why ? Look what it's done to the economy !