The example you've provided of making it difficult to return an item (and thus also difficult to claim a refund) is growing, and it's something that I have also seen on Amazon.
As for Ebay I refer to it as the "place your grandparents go to get scammed" because there are simply too many gaps in their processes that allow scams to flourish and Ebay's customer service are only permitted to accept very specific types of evidence. This inflexibility allows scammers to thrive there.
I personally swore off Ebay after dealing with another type of scam that was operating in the UK. Whereby Ebay recognised unregistered mail tracking labels as if they were a fully tracked courier service. Scammers in the UK caught onto this error, providing a scam which goes roughly like this:
1. You buy expensive item on Ebay from scammer (usually a hacked account).
2. The scammer acquires Royal Mail tracking labels. (It's possible to pre-purchase them as Royal Mail aren't going to record the delivery address, unlike a fully tracked service where each label is associated with an address and parcel specs.)
3. The scammer assembles a basic parcel and addresses it to an address that is near the victim, but not exactly the victim's address. Typically the address will be a nearby convenience store as they will sign everything that comes in.
3. The scammer applies one of their Royal Mail tracking labels and drops off the parcel in a post box.
4. The tracking label's barcode is automatically scanned as it passes through sorting centres, however the address on the package is never recorded by Royal Mail; the tracking is effectively solely for the label.
5. The parcel is delivered to the false, but nearby address. The Royal Mail system receives a signature, a GPS imprint and a time of delivery - but crucially again the address is not recorded by Royal Mail.
At this stage you can see how the scam comes about. All a scammer needs to do is send anything to a nearby address and Ebay will deny refund requests because the scammer has a tracking history from Royal Mail.
However to be fair to Royal Mail, their website for this product clearly stated that it was not a fully tracked service, a nod to the shortcomings of the approach. I believe the product has now also been discontinued, instead now a photo of the delivery is taken - which would provide useful evidence to stop this kind of fraud.