Thanks for this detailed reply. Much appreciated because I learned a thing or two.
> Did you ever try?
No, not Delhivery kind of specialised courier. But in USA I was eBay user. I was an ordinary bloke with 9-5 job, and used to sell excess stuff (old gadget which I want to upgrade from), shipping charges were major part of the transaction and my endeavour was to minimize it - ended up using US postal service quite a few times.