They are wildly different businesses. Ebay is not in the business of holding physical goods, they are a marketplace that connects buys, sellers, and shippers and adjudicates fraud, collects funds, handles taxes, etc. They are not a warehouse.

Gatestop is a retail operation that buys and sells goods. It takes on all the liability for fake products, it puts capital on the line to purchase used goods, it is a totally different (and worse) business