If you're saying that the seller should select untracked postage, but provide tracking anyway when they post, then they'll have to price their postage accordingly. And buyers are not going to pay $9+ if the item says "untracked". They will most likely assess the listing at a glance, see they're not getting tracked, skip the purchase completely and move on. Maybe some will communicate with the seller, but many won't bother.

Sure, it technically bypasses the tracking requirement but at the potential loss of sales.