Nope - if 2 people have the last of an item in their cart, only the first guy to complete the purchase will get it, the other guy gets an out of stock message. There are a ton of open carts at any given moment. Some are humans, some are bots. People price shopping, checking out shipping expenses, etc. The vast majority of carts do not end up in a purchase.
Imagine, I could go to a site and put all of their inventory in my cart and they would not be able to make any sales.
We have had a few people make a check/cash purchase on a hot item, then not pay us. We may wait weeks for the payment, and then cancel the order, finally releasing the stock for someone else to purchase it. It sucks, and why you do not see many sites willing to accept that sort of payment.