There are no chargebacks in Bitcoin. If you use this chain you must be 100% fiscally responsible for your funds
Discussion
Actually there is a mechanism. Satoshi had the foresight to describe it. You can google it for yourself.
If the transaction has not yet been confirmed on a block then you can cancel it, but you cannot reverse a confirmed Bitcoin transaction. There is also escrow but the escrow provider has to be a trusted entity
Satoshi:
Here's an outline of the kind of escrow transaction that's possible in software. This is not implemented and I probably won't have time to implement it soon, but just to let you know what's possible.
The basic escrow: The buyer commits a payment to escrow. The seller receives a transaction with the money in escrow, but he can't spend it until the buyer unlocks it. The buyer can release the payment at any time after that, which could be never. This does not allow the buyer to take the money back, but it does give him the option to burn the money out of spite by never releasing it. The seller has the option to release the money back to the buyer.
While this system does not guarantee the parties against loss, it takes the profit out of cheating.
If the seller doesn't send the goods, he doesn't get paid. The buyer would still be out the money, but at least the seller has no monetary motivation to stiff him.
The buyer can't benefit by failing to pay. He can't get the escrow money back. He can't fail to pay due to lack of funds. The seller can see that the funds are committed to his key and can't be sent to anyone else.
Now, an economist would say that a fraudulent seller could start negotiating, such as "release the money and I'll give you half of it back", but at that point, there would be so little trust and so much spite that negotiation is unlikely. Why on earth would the fraudster keep his word and send you half if he's already breaking his word to steal it? I think for modest amounts, almost everyone would refuse on principle alone.
Satoshi's genius eliminated the need for a trusted third party in this as well.
The code for the BIP would have to be well inspected as we don't want to have an ETH DAO situation with backdoors, etc. This would be useful for adoption I would think. Although, I do appreciate the lack of having it now as people need to be more responsible and not go around flinging cash at whatever willy-nilly. I like that Bitcoin makes you take personal responsibility for your cash.