What I'm writing isn't meant to defend those sellers, just to explain what's going on. The whole mess started after Dave's video when many people ordered the process meter while only a low number was in stock actually (some batch of quality control rejects). The online shops overstated the stock since they are buying from the same company/warehouse. If that warehouse has 10 units in stock and ten shops list also 10 units being in stock you end up with 100 units in total. So the meter was oversold. Since AliExpress punishes sellers when not shipping the products sold the shops are trying to work around AliExpress by entering a valid tracking ID from some other sale (possibly from another market platform). Everything looks fine for AliExpress. Then they tell the buyer some excuse for not shipping and offering to send something else or to refund via PayPal. PayPal is outside of AliExpress' view. The buyers are refunded via PayPal, AliExpress sees normal sales and won't punish the shops, no harm done besides disappointed buyers. It isn't an intended fraud, it's the result of working around a system the shops can't change.
So if you were selling a product lets say your Fluke multimeter on Ebay, would you list it ten times ? Ofcourse not.
So why do they list hundred items in stock while they have 0 in stock ? Only one answer: greed, at the risk of the customer.
The shops should list reasonable stock numbers lets say 10 meters or even 5 meters when they have no stock themselves.
After they ordered the next day and get a confirmation from the warehouse it was honoured, they could again raise the virtual stock level to 10 or 5.
This would insure:
1) That not 100 people or even more can buy this meter from you at the same time as now has happened.
2) You would worse case have to disappoint 5 persons which even with 5 x 1 star ratings should not be a problem
3) Honesty: you could tell the buyers that you were not able to get the requested item and can even give them a little 10% extra refund for their trouble.
But now they have dug a huge pitfall for themselves, not only do they get bad reviews and angry customers complaining to aliexpress, they also have lost one very important and expensive part of any business: goodwill and reputation. I guess they are finding that out now.