Perhaps an Amazonians could contribute to an open source retailing platform
I have long studied Amazon's business model, and it relies upon quantifying and avoiding/passing-on risk, and creating size-based inertia.
Their greatest strength is still in the cost & time-efficient processing of orders and managing their retail offering to customers, and then using the Marketplace to outsource all of the product research and data creation to the marketplace users, who pay a fixed 15% of their turnover on Amazon to subsidise Amazon's retail arm - then producing performance data that directs their buyers to go direct to the best trending products to take the full margin for the products most valuable to stock in-house. It's a win-win platform for them.
So they offload all the 'risk' to the small businesses, that then do the leg-work, for them to come in and wave the big brand and open chequebook to manufacturers, to cut the marketplace resellers out and grab the full margin. I have personal experience of this.
Then, once they squeeze the competitors our of the market running at low or even negative margins for a while, the price goes back up, sometimes higher, and the marketplace vendor then goes back to finding new lines to list and sell and the cycle continues - it really is a perfect-storm where the house always wins with a guaranteed minimum 15% margin on everything that other people list on the platform.
Then their customers also pay Amazon, with the time-effort in creating original content - in the form of all the product reviews - to keep their website loaded with search-engine friendly original and extensive content - for free.
I see the only way to compete against this business model is to commodities commerce platforms and ERP systems as a platform-as-a-service - to the point that anyone that would normally direct their heavy lifting market creation through the Amazon marketplace, can do the same thing themselves with their own channel, fed into a number of competing shopping search engines.
Then make an open-source product-review database, wiki-reviews if you like, that offers a barcode matching plugin to any commerce website to effectively remove the value of reviews to any one outlet other than the customer reading them on ANY website.
Perhaps if Amazon engineers wanted to contribute their knowledge and experience into an open-source platform that looks like it has the potential to do that, then the Ebay & Amazon 'small business dreams machine' will burst - and the people doing the work for them, building products and brands, will be able to cut them out and sell directly to consumers - therefore saving people the "Amazon Tax".
There are surprisingly few, but perhaps that is because people say they want to do good things, but then rarely find the time to contribute what they say they will due to the rest of the bureaucracies life creates to keep us distracted and entertained.
The closest thing I have seen to this is a small project called ERPNext and others others, 1C-DN, OpenERP, ERP5. But ERPNext seems to me to be the cleanest codebase, most open, best usability and understanding of business processes needed for ecommece, data integrity and integrated workflows for business functions.
Having spent years looking at closed-source ERP systems, I am baffled who open-source hasn't yet come up with something like Microsoft Dynamics to up-end these dominances and hand power back to product innovators and creators.
If you don't like Amazon's way, do something about it, re-direct your own experience and ideals into an open source project that makes their retail platform and ERP systems for fulfilment optimisation available to anyone. And make it better.
I know our team will be contributing some effort towards these aims, and if you can't code, maybe find another way to help one of these ones you - if think is a worthy alternative to the status-quo.
A foundation needs to do for ERP PaaS and Reviews, what Wordpress and Wikipedia did for blogs and encyclopaedias. Knowledge and journaling sharing made the internet useful, and efficiencies in supply-chains should make it improve the quality of life for everyone with cheaper products and more time to invest in contributing to society.
Remember, Bezos trading background taught him most importantly how to measure and pass on risk (to the marketplace resellers), so that he mathematically minimises the risk of wasted time/money/resources - and keeps the odds stacked in Amazon's favour.
Think of Amazon as more of an automated quantitate trading algorithm, but for brokering products, instead of stocks & shares, and you can see how, like casinos, the more they are used, the more profitable they are. If you want that to change, there has to be more cost and time efficient alternatives to make them irrelevant and remove the fuel from the fire.
Understand how to make a more efficient connection between product creators and consumers, and your free market evolution will make their middle-man tax an inefficiency - and eventually make them an expensive irrelevance.
Have a look at the BBC Panorama documentary on Amazon if you need any further inspiration as mention by a few others here.