If that is a fear shared among the general population, shouldn't that be a clear anti-trust concern?
Is losing your Amazon account that big of a deal? Are there really no practical alternatives? Is this fear of displeasing Amazon rational? If so, how come I don't hear any bells going off in government regulators?
This is a concern for people who have a lot of digital content under Amazon's umbrella. I have hundreds of audiobooks, ebooks, music, and movies - and if I lose my Amazon account I lose access to hundreds if not thousands of dollars of content.
As for trying to constrain Amazon to play fair, and treat the peasants nicely? Good luck.
Amazon is a rival to Google in terms of content delivered to people, and, like Google, Amazon performs a lot of services for the federal government. They have lobbyists, legal teams, and even politicians in their pocket.
Your subjective experience, or a lack of interest from legislators, does not mean these issues do not exist.
This indicates to me that the assets you put into their control are disposable for you or that you have no reasonable alternative. The former is easy for me to believe. That latter is difficult for me to believe. Together, it makes me disinclined to feel that the government needs to take any action on your behalf.