Yes, it is true that eBay/PayPal will force refunds for items that have not arrived. I think that the only hope that a seller has is to send via registered mail, and show eBay/PayPal that the registered items are marked as "Arrived" by the corresponding postal service. However, I have noticed that a lot of registered mail that comes to me is usually just put in my mailbox, and sometimes it is marked as "Arrived" or "Delivered" and sometimes it remains "In Transit" forever (even though I have received it, and have given feedback on eBay).
Technically either the buyers or the sellers could take advantage of the inherent flaws in this system. However, there truly is not way to guarantee anything on a sale-per-sale basis. The only true way to combat cheating and theft, is via the feedback system on eBay, which will begin to make a seller look bad, but only over time (ie. if the feedback indicates that items consistently do not arrive on a regular basis) or make a buyer look bad if he complains a lot based on the feedback he has given. No single transaction is guaranteed.
But there are definitely countries where the postal system is being pillaged by its employees. There are definite patterns and data. For example, I consistently see sellers that refuse to sell to China, Russia, Italy, etc.
One day I will become a seller, but I am definitely not looking forward to the headaches. I think the first year or so will definitely be a "learning by trial and error" (not my favourite way to learn).