Maybe Amazon is behaving badly, trying to scam customers by selling them fraud products at inflated prices. Is the best response to that to enlist the federal government to make them run their business differently? Or may we could just, you know, take our business elsewhere?

Taking your business elsewhere only works when individual customers represent a significant proportion of a company's income. With the volume Amazon handles, any individual attempt to send market signals is completely drowned out by noise and marketting. To send such a market signal strongly enough to be received, you would have to have an advertising campaign on the scale of another massive corporation. That indicates market failure. It is well known that markets are not resilient against tragedy of the commons, prisoner's dilemma, and similar phenomena.

While I am no fan of the federal government, I am even less of a fan of a federal government that is dwarfed and captured by the power of giant corporate conglomerates, nor am I a fan of corporations large enough to act as governments in their own right. Therefore it is necessary for the size of the largest businesses to not exceed the power of the federal government, and it is necessary for there to be actionable antagonism between the interests of business and government.

Markets can only be free if this balance of scale between public and private interests is maintained.

Amazon is a giant tax revenue generator for state and federal governments. It would take something quite significant to get to that level, in my humble opinion.