I haven’t actually researched these companies but it appears eBay is the used goods auction market leader and amazon actually has a distribution network as a direct retailer including partnership deals with small business and other online retailers.
I really believe there must be some synergy by merging these two (potentially continuing a separate brands) because eBay with its PayPal business is a trusted name in auctions but seems to be competing directly with amazon by selling new products through honline retailers and small businesses also.
I like both of the companies but a merger would consolidate Amazons market share