I have not encountered that, not once, so it may depend on the types of items you are buying. One thing you could try, - when you see an item you like, you could ask the seller if she has it in stock and if it is available for mailing.
Either way, sellers have 7 days after cleared payment to get an item in the mail to you. It's nice when they ship it right away, but they are permitted a week, - so allow them their week.
If you need an item in a mega-hurry the seller may be willing to ship it by overnight courier or some such thing, - but you understand what that will cost, of course.
Otherwise, one way to avoid drop-shippers is if the seller's ID is registered in one country but the item location is in another. Same with some consignment sellers, but you may want to ask about product availability to be sure.