Well, I’m sure exposure has a lot to do with it, mainly because Amazon has really good customer service and people can file an A to Z claim if something goes wrong, where as eBay has pretty shitty customer service and you’re more likely to get screwed over if something happens. Amazon also takes the hit if a customer pulls a scam so I don’t lose my money or item, where eBay offers little protection on the sellers end (like if someone claims an item never came or arrived damaged). Here’s an example:
LEGO Simpsons 71006 The Simpsons House https://www.amazon.com/dp/B00HX14C7Q/ref=cm_sw_r_cp_api_glt_fabc_01MTH301RJ94RX78W3PX
Same item, but seller will get less on eBay and have little/no protection if buyer makes a claim.