Here is an example only.

Problem:

The buyer purchased 5 security stickers for $6 on the 1/1/2018 and the seller  being competitive by offering the buyer with free postage using regular letter service which is not trackable.

After 9 business days the buyer has still not received the stickers and file an item not recieved case.

Outcome:

The buyer won this case because the seller doesn't have any evidence that the item was delivered and couldn't provide the tracking code that the item was delivered.

Resolution:

What eBay should now do is adding to their existing policy stating:

1. The seller is not liable for the item(s) are lost in transit when the buyer used a non-trackable shipping method.

2. If the buyer used a trackable shipping method and the item(s) are lost in transit then do seller will help the buyer with item(s) recovery or compensation.