About a decade or so ago I was able to get a couple of bad feedbacks deleted by Trademe. Two separate buyers were upset about the shipping delay. Auction finished on a Wednesday, I sent on Thursday, then it was Easter weekend so they didn't get their packages until the following Wednesday. I was able to prove that I sent it on that particular day, and it still took the advertised 2-3 business days. Not sure if Trademe do that any more which is a shame.

Because of the amount I buy and sell on TradeMe I have a feedback day, which is the 1st of every month. I place feedback for everything from the previous month all at once to save time. I do know what you're talking about though with many people never placing feedback. I'm pretty sure my feedback star rating would be almost double what it is now had every person placed feedback. Before the days of parcel tracking, I wouldn't even know that a buyer had received the package.

I always print my own labels. Sometimes, after the label has been generated by trademe the address is slightly wrong and I am able to change it before leaving it for pick up. The courier companies won't know to do this if you get them to print them.