The best way to respond is to build tools that allow the market to bring high quality shops to the top, and lower quality shops that provide poor customer service or fraudulent products to be suppressed. In this way, the consumer benefits through the consumer experience of others.
Shopify is a little too close to their shops to be able to provide this type of tool, because they have the obligation to support each and every one of their shops.
Third party search engines, built to support the Shopify platform are able to implement these types of tools and bring a user curated shopping experience to shoppers.
So, you're right in that a search bar can shine a spotlight on the dark corners of e-commerce, but that doesn't mean that there aren't ways to create a better experience.