A quick Google search of "price comparison sites" surfaces articles like this:
https://www.shopify.ca/blog/7068398-10-best-comparison-shopping-engines-to-increase-ecommerce-sales<p>The majority of these sites look like they haven't been updated a decade.
Seems like a second order consequence of optimizing for SEO. Google takes time to index websites and as a page accrues search index strength, by the time it becomes a top result, the actual content is likely out of date or irrelevant. An adverse network effect perpetuating less relevant information rewarding being first / existing for the longest period of time.