If you are reading this and have the potential to make take such an initiative , please do and we, the Bitcoin community will support you.
With over 13,000 employees at eBay, I'm sure they are aware of crypto. If there was an advantage to their current model to use crypto they would have implemented it already. And like the previous poster wrote, there are still fees with crypto, and the company needs to make a profit.
I don't think any developer here would spend thousands of hours making an eBay clone if they couldn't charge fees, and the instant it started making money, eBay could add it on easily.
What you want is an auction site that doesn't need to refund/return.
People can't understand one thing: What you want and think is amazing, doesn't mean that others share the same thoughts and opinions. Most people can't understand that for example if Ebay doesn't implement cryptocurrencies, there are a reasons behind it and at the same time if someone hit market where there is open monopoly. Anyone can enter into market but no one can beat the giants. If someone wants to enter in this market with cryptocurrencies, it would cost a tons of money and then, the same action from Ebay (implementing of cryptocurrencies) and this business will dive and lose billions.
What kind of fees do a crypto version of Ebay would be able to save? Do fees change when you pay with Euro over USD? Or GBP over USD and Euro? Or take any other national currency. I want to remind you that Bitcoin is a currency, different from traditional ones but still a currency and it's very easy from governments to set fees on it the way they wish and in terms of fees make it absolutely similar of the situation we have right now on Ebay.
Cryptocurrencies aren't magical things or spells.