1) market competition: if there's no (better) competitor and you need the services provided for whatever you need, how can you vote with your wallet?
2) Price: I'd love to buy ethically sourced-everything, but I simply cannot afford it and will never be able to (on my current income) as long as unethically sourced remains this much cheaper and the norm. Income and market prices adapt to each other.
3) Knowledge & time: It is incredibly time and energy consuming to find out all these things. Amazon has now made the news, but how do you know which competitors are better? Look at food, even with all the labels we have these days there is still a lot of misleading information out there.
4) All of the above and more applied to everyone: As I mentioned, the above probably doesn't apply to most of the HN crowd, but any of these reasons (and probably a lot more I missed) would be enough to stop someone from voting with their wallet. In order to do so you must have the knowledge, time, energy and availability. Something not everyone has. If but a small minority can (and wants) to vote with their wallet, it will almost never be cost-effective for companies to change.
Whatever happened to good old fashioned legislation? One can make a similar argument for voting (time & knowledge limitations mostly), but they should be less severe barriers.
Really, how many of us need to buy office supplies, diapers, or groceries from amazon? How many times do you need to have a book delivered to you in less than X hours? We have these fabricated needs and companies that provide services to fulfil them, which really says a lot about the power of their marketing.
Again, not disagreeing with your arguments, I just think they dont apply to the majority of the cases, where you can avoid amazon and just shop elsewhere (slightly less convenient, I must say - its a matter of values, and voting with your wallet)
Its important to note that when you buy a product, you are essentially voting with your wallet, saying "yes" to a company, its values, ways of operation, impact on the planet, etc etc. Its easy just to pass this as an internal amazon problem, but if you still buy there, you are supporting it anyway.
I've stopped using Amazon 2 years ago, dont miss it, and dont think I will.