Because they don't have the same unlimited inventory capacity, local stores have to put at least some effort into selling products with some base level of quality and focusing on the products most likely to sell in each category. Local stores are by no means perfect here, but they're vastly better than Amazon in this regard. And it's especially important because finding good independent product reviews on the internet these days is also a challenge, and even where they exist they're not reviewing whatever no-name Chinese brand Amazon is selling anyways.