I had this twice with two G1 ponies years and years back. Both MOC, both came off their cards as a result of transit, so ended up being mint loose ponies. The second, Wind Whistler, I negotiated with the seller who took responsibility for the packing and refunded me partially. The first, nothing at all. That was Watercolor Misty and he sent her in an envelope - not a padded one, a regular one - via SURFACE mail (which took 4 or 5 weeks to get to me). Of course, this was not my decision; but back then a lot of sellers chose to ship surface to the UK instead of air because it was cheaper and they felt it offered a more competitive rate.
I am amazed her card isn't more damaged, but she fell right off it the moment I opened the envelope.
I recently bought some wing replacements for MH doll Rochelle and the seller sent them in a normal envelope without padding. No idea how they didn't get smashed. I also had a couple of dolls in basic envelopes which our postie tried to shove through the letter box (and they got stuck). I had to realign Jackson's hips, as the whole endeavour dislocated both of them (but didn't break the elastic, thankfully, he's fine now, if a little shaken xD)
People shipping on ebay need to understand that even if they want to offer competitive shipping prices, it isn't good PR for them to ship badly. They should consider themselves responsible for damage in the post that occurs on account of their poor packing, since we all know that post gets tossed about a lot. I always worry about delicate items I send even within the UK, although they always go in boxes with lots of bubble packing. I can't imagine sending anything really fragile in a basic mailer.