The block time is 2 minutes. You can choose to wait for 0 blocks or 100. The longer you wait the better the security of your transaction, because there's more PoW behind it. All crypto work like this. You also get more security behind your tx by waiting in a PoS system.
If you're buying a coffee the vendor is likely to let you leave the shop after no confirmations (as soon as their node hears about the transaction) but if you're buying a car the same is unlikely to be true.
> but if you're buying a car the same is unlikely to be true.
I don't see why not, it's not like you can buy a car anonymously. If anything there's more security there than with the coffee, and no one is going to attack the Monero network to create a double spend for the price of a car.
In practice people (e.g. exchanges, that know who you are after KYC) still opt to wait a little because if something does go wrong it's a hassle to actually get paid. For the same reason, we are likely to check some of the bills in a large cash payment for authenticity, even though we have effective recourse through the police and the judicial system.
If you're buying a coffee the vendor is likely to let you leave the shop after no confirmations (as soon as their node hears about the transaction) but if you're buying a car the same is unlikely to be true.