> what is the consumer harm
Fires from bootleg phone chargers and the like. (Google for "phone charger fire" to see how often this happens.)
Explosions from bootleg batteries.
Sickness from bootleg water filters and food.
What if you bought CO/ALR receptacles to bring a home with Aluminum wiring up to code, but the terminals weren't made from Indium?
What if you bought a marine battery for your sump pump backup, but it failed to perform and/or failed to notify you of its impending death?
I can continue from here, but I think you get the point.
That being said, there is a lot of stuff on amazon I'm honestly surprised is worth the space it takes up in their warehouses. And I have knowingly bought some low-quality stuff on amazon. But perhaps with the critical caveat of knowingly, I have yet to have a counterfeit foisted upon me.