because the evidence ebay believe shows delivery to a location. Note its not just simple delivery here - even if it was custom delivery - ebay would use the same evidence.

Other marketplaces will believe a buyer if they state they did not receive their parcel, even with that evidence. In that event - sellers lose out because it opens it up to fraud. Just say you didn't receive it - they'll just believe you and refund you.

So if you don't like ebays terms and would prefer to have a bit more security in the instances where couriers deliver, but don't - the answer is shop elsewhere.