Nowadays, 3rd service such as Coinbase or Bitpay accept 0 confirmation transaction. Some merchants also accept 1 to 3 confirmation for a transaction now.
But, for big transaction, i think few confirmation is still needed because 2% is still risky.
Agreed with this. Like anything it is a trade-off between convenience and risk.
Buying a coffee or some low amount for $20-30, 0 confirmations would be fine as the risk is small and the inconvenience the make the customer wait around 10 minutes is great.
Medium transactions of $100+ you might want 1-3 transactions, but by then it is pretty safe, and asking someone to wait for 1 transaction in not unreasonable. Think maybe a shoe store, you buy $200 shoes and they ask you to wait for 1-2 confirmation, probably not a big deal.
Large transactions, maybe $10,000+ you would wait for 6 or more confirmations to be sure. Say you buying that Tesla for $100,000 using bitcoin, It would probably take longer to fill out all the paperwork than the time it would take the 6 confirmations to go through.
This is no different than a bank holding large check deposits before you can withdrawal against them. I can deposit a $100 check my grandma gave me for my birthday and spend it the same day. I deposit a $10,000 check and they might let me spend $100-$200 of the funds right away, but they will hold the rest of the balance until the check clear sin 2-3 days, which is a lot longer than waiting around for 6 bitcoin confirmations.
Update: franky1's comment was not there at the time I wrote this post. Seems in a matter of 3 minutes we had the same thoughts.