That's incorrect. "Amazon's Choice" is based on sales. If you search "flash drives" the product that has the Amazon's Choice badge is the product that is bought most often by customers using that search term. It's one of the only organic things on the Amazon platform.
It only vaguely verifies that it's in the same product category though. For the "1tb flash drive" search term, Amazon's Choice includes a 128GB flash drive, a 1TB HDD, a 2TB HDD, and a single 1TB flash drive.
It's broken down by price ranges... but it's like going to a car dealership, inquiring about a compact car, and being presented with a skateboard, a road bike, a mountain bike and a car.