regarding quantity of incidents occuring, i know someone who works at fedex, & they deliver ~4 million parcels every day. (i'm sure ups' volume is a *lot* greater.) if fedex has a 99.99% successful delivery rate, that still means 400 packages lost/damaged every day.
i think folks have to be a bit more realistic w/their expectations. as said before, over-pack, get as much buyer-seller info as possible, and make sure the merchandise is properly insured.
doug