Re: I wish the competition commission would do something useful instead...
What you are failing to take account of there is the completely dominant position of Amazon in the e-commerce marketplace. You say "they just can't list it on Amazon if they do" as if that's a non-issue, however for many small companies (not the one I work for thankfully, as we have a brand and a long-established customer base of our own) selling on Amazon is the only way to stay in business; not selling on Amazon is effectively not an option if they wish to continue to pay the Mortgage.
"There is no reason for Amazon to not protect it's customers by asking retailers to ensure that they are not charging more on Amazon than through another outlet"
There is a very good reason for Amazon to not do this: this is price fixing. Don't just take my word for it, the OFT seems to agree.
And if you think that this activity s 'to protect the customers' you are hopelessly naive. For reasons explained several times throughout this discussion, the end result of this activity is higher prices for the consumer, because smaller retailers are basically having to build the Amazon tax into products even when selling them elsewhere than Amazon.