You don't, though, which is the other person's point. Unless you've radically changed your consumption habits to only buy directly from producers (and ecommerce is ruled out, since you're not okay with the typical conditions of logistics employment). In reality, you've singled out Amazon. Which is fine! But at least admit that. It's a political statement, you haven't achieved labor rights veganism.
Off course, it is totally fine to participate in things and also criticise them, as that is how things improve. But if everyone obsess on a company not in the bottom of bad behaviour, this simply gives more power to companies behaving worse. One can off course claim that their criticism depends on the PR perception of the company,but I guess that's not fashionable.
I don't think the argument is everyone else does it. The argument is Amazon is paying much higher than many other companies for the same job, and still being focused over, while companies paying less get a free pass.
Edit: or maybe not.
Interesting concept when you consider how deep the supply chain is for all the raw materials. The provenance on lithium and silicon would be critical I'd think.
You also seem to be applying black-and-white thinking to problems of right and wrong. Some things are more wrong than others.
On a scale from "single mother cheating on her taxes so she can feed her kids" to "cold-blooded murder," Amazon is (in my opinion) beating puppies with sticks. When someone does something not just wrong, but inexcusable, and is unapologetic, I don't say to myself, "well, lots of other people have done/do bad things." I doubt you do either.