[probablybroken]

The only way for Amazon to do what you ask is to not allow third parties to list products in their system at all, and to verify continuity of supply by continually spot checking product, and penalising vendors for changing spec on them.

[creato]

I think that's the point. Most retailers do exactly what you describe, and I prefer buying things at those stores instead of Amazon because of it. But that's just me.