Why do some Amazon listings have tens of thousands of reviews for the same-looking scale?

The Travel Inspira and Etekcity handhelds have been on sale for many years with multiple ASIN variants, so cumulative review counts in the 10,000 to 70,000 range reflect listing age more than any quality leap over competitors. The volume is useful as a longevity signal but doesn't, on its own, establish that any single unit outperforms a near-identical rival.