You may get away with some small parcels now and then as a private user if their value is declared and low. Heck, you may get away with a no value, no insurance "gift" now and then. But for the rest... I exported to 90+ countries in the late 90ies early 2000. Always the same type of thing (my product) so paperwork was essentially a meticulous routine. But paperwork there was... Incidentally, our software fell, at least partially, under ITAR (when it became a thing)
https://www.millercanfield.com/resources-417.html too...
The sender remains responsible for what he sends. In fact, the actual sender is more legally and financially exposed than the buyer. By default, if what he sends is illegal in some way (which these days could simply be an improperly sent battery) for example.
If the buyer abandons the goods (say a pair of speakers), they will only be returned automatically if the sender has provisioned the fee with the carrier, or if the sender pays the return fee when informed by the carrier. Other than that, it gets destroyed, impounded and sold, storage and administrative fees pile up, depending...
If UCC, Incoterms, HTS US etc don't ring a bell, you are really talking without knowing the subject, or in other words, your post are poor quality goods sold FOB