I think of it this way.
In the US. if you have a major project going on, you'll end up using what you can and what you tear out to upgrade tends to just go in the 'bin', whether that's just trash, or not worth the companies time to inventory and keep... The US standard is either toss it, keep it off the books just in case, or somebody nabs it for secondary use.
China and India tend to be scavenging for profit type. So if something is not quite right but isn't sellable, it ends up being sold on ebay or aliexpress. and same for old equipment, everything has a value because there isn't any value in just abandoning things there. Take a 2-300 dollar chinese process meter that EEVblog had a thread about a while ago. Somehow there were hundreds of multimeter/processmeter units being sold for 7 dollars each...Shipped... and when they were torn apart, it was discovered that they were genuinely decent sim/source devices with TI chips and everything. The kicker was that some worked good, but a lot had functional issues that were extremely obvious.
The dirty secret is that the stuff was probably factory rejects slated for disassembly or destruction, and somebody got ahold of a bunch of them and went to town making a quick buck on what would have been trash, but now was just marginally functional. legit packaging and everything...just sub par quality not suitable for the standard 300 dollar pricetag.
buyer beware if the deal looks too good to be true.