I completely agree. And if it hasn't, then it's almost certainly occurred, not necessarily because the sender hasn't packed things properly (after all, aside from blatant neglect, "properly" is subjective), but rather that the sender hasn't packed things
sufficiently well enough, for the contents to survive the abuse they're liable to be subjected to in transit, through careless handling by couriers, or whatever.
*That* is the real problem. And which is why, once you think that whatever you're sending to someone has been 'packed properly', pack it some more, just for good measure, as the extra layer of protection applied at that point, may just be the difference between the item getting to its destination intact or not!
I've sent stuff all over the world, and some of it extremely fragile, without any problems, such as a matched quad of NOS GEC KT88s, to Australia, minus their original boxes, which despite being handled, en route, many different times by different people, got there safe and sound.
One thing I've found that usually works well, is to thickly bubble-wrap EVERYTHING, whether you think it 'needs' it or not, and double, or even triple-box stuff, so that the contents have as many layers of protection around them as possible. Crucially, you also need to ensure that what's inside is completely prevented from rattling around, as that's often how damage occurs.
Consequently, the size of the package those valves ended up being shipped in, was about ten times bigger than they were!!
At the end of the day, it's
YOUR responsibility, as a seller, to do as much as you can (and put in the required effort) to ensure that the person who's given you his or her hard-earned cash gets the goods that they've paid for, in the SAME condition they were in when they left - and in that respect too many sellers are lazy. After all, in most cases, full payment from the buyer will already have been received, so often the motivation to 'go the extra mile', in that respect, is lacking...
However, deliveries of items from commercial companies, shipped inside custom-made cartons and packaging, such as you're referring to, is a different kettle of fish from private sellers shipping items to buyers, often without access to the original boxes and packaging, and having to utilize whatever he or she has available, so I'm not surprised that you've experienced no problems with the former - you really shouldn't!
Marco.