DaveDog: At the risk of stating what I see to be pretty obvious, but if you're not happy with how the seller chooses to send their goods, don't purchase from them and try elsewhere...
I don't sell a lot on Trademe, but when I do I use Pass the Parcel - Not because they're the best, or the fastest, or the cheapest but because it suits me - I'll always state in the auction that's how I am going to send stuff and the buyer is free to buy (or not) based on that...
I don't want to post stuff, I don't want to courier with other companies simply because I don't want to faff around doing so - I have the PTP bags and boxes on hand and it's low hassle...
This is not always possible (when buying from retailers) because sometimes you do not have that much choice which one and they often do not disclose which courier they will use, or use more than one firm depending on the cost.
Pace are very good. I once ordered a telephoto from Auckland which I needed to cover a story the next day. Pace booked a seat on the next flight down from Auckland and it was hand carried off the plane and given to me by the Air NZ staff! Cost me $181 to ship it...!