My experience with having small orders shipped from the US to Chile by mail, since about 1980 until nowadays, is like this:
In the beginning, there was airmail and surface mail. Airmail arrived quickly but the cost was too high with heavy items. Small items mailed at letter rate in an envelope, about $1, while items up to about 2 pounds mailed as parcel post for about $7. Surface mail was very inexpensive, like $10 for a big box full of heavy stuff, but took 3 months to arrive and often smelled of fish and algae.
Later, like the 1990s, there were three options: "First class mail", which was really last class, "Priority mail", and "Express mail". Shipping small items as letters was no longer legal, but some sellers did it anyway. First class mail sometimes didn't arrive, as it was nonlisted and nontrackable. Priority mail was the way to go: It arrived quickly, it could be registered, and a typical small box full of parts, large enough to put in a NanoVNA with its own box, cost about $14 to ship. Express mail was more expensive, registered by default, but wasn't any faster than Priority mail. In Chile all three systems were handled the same. And all came by air. The only difference was the handling in the US, and the priority level to get on a plane. When planes were chronically full, typically before Christmas time, "First class mail" parcels apparently were left to rot, or taken home by the someone.
The later developments were basically drastic price increases, ever more restrictions on what can be shipped, also on size and weight, and an increasing unwillingness of US companies to ship by mail at all, trying to force customers instead to make do with super-expensive Express companies, that deliver in 3 days, but only ever to street addresses in cities. All those of us who live in the countryside cannot get anything through any Express company! The postal service instead holds the parcels at the nearest post office, for pickup by us rural hillbillies.
Shipping from China, when it started, was usually by China Post, Hongkong Post, apparently some sellers also had access to Chinese offices of foreign postal services like Singapore Post and even Deutsche Post. Typical charges for airmail with full tracking was, and still is, about $4 for small items. The parcels arrived quicker than from the US. The weirdest thing I ordered from China that way was a hedge cutter attachment for my weed whacker, a nasty-looking thing full of sharp teeth. The Chinese seller just wrapped it in two layers of bubble plastic and put it in the mail. It arrived just fine, with most of the bubble wrap gone. Shipping charge was $6 or so. A company in the US wanted to charge me $400 for FedEx shipping.
But then the craze of company-run logistics began. First Amazon, then companies like AliExpress and eBay, started to set up their own shipping networks. At first they allowed buyers to choose between those and the postal service, but later they started forcing every customer to use the company-owned shipping system, or a super-expensive Express service. For years AliExpress happened to use the Chilean postal service for last-mile distribution, so that was OK with me, and I made many purchases that way. But recently they moved from postal distribution to an unknown little local shipping company, and that was the end! That company does not deliver to my entire area, not even to the town where I do my shopping, and AliExpress blamed me for that, and I lost my money.
So now I'm down to trying to find individual companies in China and elsewhere, or some few eBay sellers in countries where eBay still offers a choice of shipping that includes the postal service, when I need something that's not available locally. The high postal rates currently make the US the least attractive country in the world to order from, at least for me here in the Chilean backcountry. I have gotten parcels from the UK, Australia, South Africa, Thailand, Germany, Sweden, by air mail, not as cheap as from China but far less expensive than US postal rates.
With COVID-19 everything went crazy, it became virtually impossible to get anything from anywhere by mail, but then China was the first to get back to normal.
Dave Merrill
va3rr