To bring additional perspective to this table,
I very much agree with the sentiments of the original post. On seller profiles, there are no signs posted saying "I/WE MAY REFUSE SERVICE AT MY/OUR SOLE DISCRETION" like brick and mortar stores often have, so a buyer is often mislead to believe that the seller has made their listings reasonably accurate without a doubt, setting reserve prices as the seller wishes, ensuring that the countries they'll ship to are marked correctly, so forth.
But this isn't the case, on eBay there is no way a buyer can determine if a transaction will succeed or if the time they spent on that listing or searching in general is in vain or if the seller was lazy on the listing and didn't completely fill everything out (including setting reserve prices for auctions to ensure a minimum is had, it isn't the buyer's concern a seller is trying to dodge fees)
When you buy something at a brick and mortar store, the moment you hand the money over, it is accepted and the receipt is tendered ("the transaction"), the title for that item is transferred to you — thus why you can pay for a bottle of pop and open it right in the store. So if you say buy a piece of furniture but can't take it home immediately, the furniture may still be located at the store building, but the receipt is proof that your money was accepted and that the item belongs to you solely. When a transaction happens on eBay, eBay is acting as an agent of the seller and it is the seller's sole responsibility to ensure they provided eBay all information on expectations on how a transaction is to happen.
A seller's failure to plan for these eventualities where they "didn't get what they want" or something akin does not constitute a failure on the part of a buyer. Caveat Emptor is to be had, yes, but this is why laws and regulations exist to ensure consumers in general are protected and can pursue tangible action against a merchant that fails to perform and to seek damages and relief. A refund is a refund, it isn't relief as the consumer isn't given their time back nor anything that amounts to it they spent on searching, reviewing and finally making the transaction.
ENFORCEMENT:
As far as enforcement, it is indeed true that legally this is problematic due to the international nature of eBay. However there's ways indeed even within eBay's system.
If a seller wants to pull out, they should have to expressly indicate on the listing before any transaction attempts are made that the seller reserves the right to refuse service, to which a buyer should be unable to pay until the seller manually issues a Paypal invoice (this is the key feature here). This would mean that the transaction hasn't happened yet until the seller wants it. If they fail to enable this warning, the option to cancel the transaction should be unavailable to the seller and thus if they do not ship, the buyer can then seek an item no-show dispute.
If a seller is found to be refusing service without warning, they should have their listings suspended on an exponential scale for each infraction, starting with 1 day (2 days, 1 week, 2 weeks...). This would encourage sellers to be accurate on their listings and to ensure buyers are aware of the sellers who may cancel at any time. It would also financially impact sellers who refuse without warning as their other listings couldn't sell while suspended and also prevent them from immediately re-listing the item they just canceled on. It would grant the buyer relief as they know the seller has had concrete action taken against them.
If a seller DOES list with that warning, then a buyer should be capable of too walking away from the at any time, be able to cancel themselves right up until that invoice is issued (constituting acceptance of the transaction: "Go ahead, pay me, I accept", having their hand out at the cash register so-to-speak). Obviously a buyer would be penalized for every unilateral cancellation they could do, rate limiting them from rapidly buying on those listings to prevent abuse, then canceling, to which the first would be 1 hour until they can make their next purchase attempt, then exponentially again, 6 hours, 12 hours. Then when they get to 1 day they would have to contact eBay customer support to have their account unlocked and explain why they were rapidly canceling on those types of listings. Obviously in this mode, a seller would not be penalized if they provide this warning (which would be notable and be before the item description) and turn down a purchase from a buyer.
The point is, the current system provides buyers no tangible relief, just refunds which are little more than a spit in the face to sellers as if saying "Your money isn't good enough for me, go away".
