Wait, what problem is this supposed to solve? You don't have the "fast transaction problem" when ordering things online.
Yup, payments show up instantly and are probably good for most cases. No need to wait for confirmation. But how in the world can I buy a 2000 BTC car without waiting an hour! 
That's not the point. Online, you'll have plenty of confirmations long before the product gets into the UPS truck. (If you're selling digital products like e-books, then you have to wait for a confirmation or take your chances.) For transactions conducted in person, the seller simply needs to be reasonably sure that you didn't attempt a double spend attack - which itself requires careful timing and some luck along with >50% of the network. And in any case, if you tried it on the car dealer, they could just call the cops. After all, they know who you are anyway.
This is the problem. There is an example: I'm in a shopping center and buy stuffs in a little store inside. I pay it (without waiting confirmations). But then, I choose going to another store, it's simple and fast, walking three footsteps there is the next store and buy again. Double spending.
That's the risk of not using escrows or intermediaries (maybe i'm wrong)
You are, its nowhere near that easy. When two conflicting transactions exist clients that have already seen the first transaction will not broadcast the second. Meaning that unless you get new peers your attempt at a double spend will be killed instantly. Even if you do manage to get new peers by the time you get a new set of connections your first transaction will have spread too much. In any shopping center all the shops will have each other as peers, the first shop received your first transaction nano second after you sent them. When you attempt to double spend over there their client will have seen your first transaction and know immediately that it is a double spend attempt.