Economically-questionable conclusions: although individual secretive utilities might on occasion make dumb deals,
  they'll charge households whatever the market & regulators will allow, 
  and then charge Amazon whatever the market & regulators allow.

Because most utilities are monopolies that are allowed by regulators I'm not sure that the market's invisible hand has that much of an impact is this particular situation. The consumers who need electricity for their homes don't have much choice here.

Edit: formatting