Not exactly. To be sure it isn't a double spend it needs to be part of the block chain at least six down from the most recent block generated. Each extra block on top of the block where your transaction exists is a confirmation. For smaller purchases, ie not $150 million worth it's near instantaneous.

Yeah, I would bet that credit card fraud with chargebacks is probably more likely than the double spend scenario so it would make sense for a company just not care about verifying.