I'm no fan of either - Allegro has Amazon executives and nearly identical Prime-free shipping strategy. Pretty sure Allegro has the same effect of monopolizing and driving up prices as Amazon has.
I find the eBay-esque artifact interface absurd. It's likely Amazon hasn't found a way because an environment that isn't a monopoly isn't attractive to begin with for that business model.
I think Allegro lowers prices because it forces sellers into common arena where they have no choice but to compete with each other. It's usually cheaper to buy stuff on Allegro than on dedicated e-commerce site.
But think about it - when was the last time you actually got a good comparison in this market between allegro and a dedicated e-commerce site? For many product categories the latter almost doesn't even exist anymore.
Maybe tipping point is ahead of us. But Allegro already has 20mln unique users monthly (in a country of 36mln people) and twice as many as next largest, AliExpress.
Allegro has amazing metadata allowing you to precisely filter out the results. Search experience on amazon is an utter abomination compared to Allegro.
I find the eBay-esque artifact interface absurd. It's likely Amazon hasn't found a way because an environment that isn't a monopoly isn't attractive to begin with for that business model.