Yes, it's a problem on ebay & I think they will have to address it one day..

Probably, in the meantime,  the best thing to do is look at the estimated delivery date in any ad. If it is supposed to be in Aust but has a delivery date 4 or 5 weeks hence, that's a bit of a flag that the item may be coming from overseas.

If you buy something listed as local and it goes way past the due delivery dates & the sellers avoid questions, open an item not received claim, don't let them fob you off.