Sounds like item WILL "get lost in the mail" according to your update. People will get their credits back if they never get it. That's why people ship with tracking..
Yes it does add up...I don't do tracking a lot either..but I tell others about my perfect feedback and tell them not to lie and be honest when items come, sometimes you will get those that lie..and it will mess up your feedback..but sometimes you got to deal with the crazy, wacky nuts on here and block them if they cause problems...I just keep on doing my auctions..and having fun..eventually the more great feedback you get...listia will recognize you as a trusted honest seller...I take pictures of each item being put into package, then the package itself with postage and winners name, just incase I had a problem then I could at least try to show listia I did mail out...