You can't single-handedly back out of a credit card transaction either. The credit card company has to agree with you and give you your money back.

Most people would, however, consider a credit card payment reversible.

In the credit card situation, it's possible for the consumer to change their mind for up to 180 days. If so, then the credit card company gets involved and things move on from there.

If I understand this BTC mechanism properly (and I've never used it, so disclaimer there), once the consumer says "yes" there's no going back as far as they're concerned. Since the merchant is going to always say "yes" right away, that means that the only way to approximate the level of consumer protection that credit cards offer using this protocol is if the consumer makes a habit of waiting up to 6 months to release funds to the merchant. Which is something I wouldn't blame merchants for not being willing to accept such a situation. Defaulting to "180 days, same as cash" sounds like a terrible business practice to me.

That's not how the mechanism works. The buyer sends the money to a special address which is like a staging area. The money cannot leave that staging area in any direction (including back to the buyer) until two of the buyer, seller, and arbiter agree on its destination.

Right. . . but once it leaves that staging area, no backsies. So in order to replicate the kind of consumer protection that credit cards offer, probably you'd do something where the buyer doesn't do anything, and instead has 180 days to vote to cancel the transaction. At the end of that 180 day period, the 3rd party automatically votes to release the funds from the merchant.

From the buyer's perspective that kind of arrangement might feel like they paid for the product right away. But from the seller's perspective, it's a terrible deal because they never get paid until half a year later.

i.e. not reversible. Once the buyer says they received the merchandise and signs off, the money goes to the merchant. If after two days the merchandise goes bad because it was fraudulent, the buyer is screwed. No 180 day waiting period.

Ok but it's a pretty involved and rare scam sending a product which arrives and appears legitimate and later breaks down.

It's one of the most widespread scams around: Sell cheap counterfeits.