Free market capitalism (specifically Amazon's method) significantly results in market dominance, a macro-economic reliance on that company succeeding, and reduces social mobility among working class Americans.
Market Dominance: Amazon has, in basic terms, brought upon the Walmart Effect throughout the US. And exacerbates the effect within the small towns where they build their warehouses.
Macro-Economic Reliance: As Amazon employs 1.1m Americans, the macro-economics of America have become reliant on Amazon succeeding. Resulting in a fear, or at least a trepidation, in interfering with whatever Amazon wants to do. The threat of mass layoffs due to any state/local/federal regulations would have profound effects of the American economy. Something that, back when free market capitalism was seen as the most equal way to ensure competition, was not possible, and most likely not even conceived as being likely.
Reduction in Social Mobility: Building off of the Market Dominance bit, this reduction in wages and revenue for small businesses/local businesses reduces the ability of everyday American citizens to build a successful business to provide social mobility for them and their children. And for employees, yes, they make great money working at an Amazon factory. But talk to many Amazon employees and they'll tell you it's grueling, backbreaking work. And when they have enough and decide to quit or are fired there are, typically, no jobs in their local area that either pay that well or that they may qualify for.
I'm not saying Amazon is forcing you at gunpoint to buy from them. I'm saying that Amazon, due to our government's failure to intervene earlier on in their growth, has crafted the free market around them, has made it to where it's more difficult/annoying/impossible to not buy from them.