I will add this as well, drop shipping vs shipping and inventory volumes are two seperate issues.
Drop shipping simply means they ship from the manufacturer, or a warehouse, directly to you when you place the order. As long as there is stock/product available, it's usually (used to be) a relative non issue, because in many cases, you actually got items sooner than if they had to ship them from a store or local warehouse, because the manufacturer had staff that did just that, ship. Day in, day out, multiple times a day, with many carriers.
It kept the shops from having to 'guess' what part anyone might need At a random momemt in time, which helped them offer a larger range of product, but not actual inventory, which kept prices AND physical space needs down. This became more and more necessary as everyone stopped physically visiting the FLAP and FLORS, and instead relied on online purchases.
Now then, fast forward to the last couple years, where a previous 40 ft container shipped for $500-$800. The cost and availability of, say quadratec to get a full container of parts from a manufacturer in China to their warehouse in the US was pretty straight forward. Order the product, divide the x number of parts by the x dollars to ship, and off you go.
Fast forward to today, and that same container can cost upwards of $6-$8K to ship, IF you can get (order) one.
If you have 12,000-16,000 pieces of, say, leaf spring bushings in that container, it 'only' adds .50 cents apiece to each of the products in it. If you are shipping jeep tubs, and you can only fit in 6 or 12 at a time, it's substantially higher per unit.
Also, with covid, there are so many less containers and boat space to be had, you have to be able to both get a container , AND find boat space. Remember, this goes for getting the materials TO the manufacturer as well.
I was just talking with a local trucking and container shipping company here, and the owner was confirming all this as fact. (In fact, his stories).
While I 100% agree it's complete and utter BS to list a part you don't have, I have to also defend the practice of drop shipping, because no one can or will pay the price it costs to have a local shop pay/hold the inventory anymore, the commerce is all done on line.
Hoss