How come a listing says one left and then once I order it it then removes the one left?

Because you bought the 1 left?

LOL No, no, no. If they had one and I bought it, then there should be none left. They are still available without any indication how many are left now.

Its done to get people to buy.

LOL No, no, no. If they had one and I bought it, then there should be none left. They are still available without any indication how many are left now.

 

Not 100% sure but I think it's because the system gives a chance to the seller to quickly say that it's back in stock (very unlikely).

I you check again some hours later and the seller has zero in stock, the indication will put "sold out".

its a feature called out of stock feature and can auto replenish items that went to 0

Its probably 1 left from that particular 3rd party seller. Once you purchased the last one, the listing will go to the next seller.