vs cash/cards in person - too slow, I can pass someone banknotes in a shop and we are done in 5 seconds, I cannot wait 10mins to 2 hours for the BTC to pass
This is something that bothers me. How will it work when bitcoins are accepted everywhere? Will I go to Starbucks, pay and then wait 10 minutes before getting my coffee???
Exactly, I'd rather use MasterCard PayPass or Visa payWave.
If we have to install bitcoin acceptance machines at Starbucks, that's going to add to costs. People forget that and point to the fact that it is cheaper theoretically, but not practically. Add wifi, a terminal and the need to secure the machine and lost business due to people waiting in line for confirmations before they are allowed to leave. You can argue to use off-chain transactions, but why not use cards that are off-chain too? It defeats the purpose of bitcoin, it isn't even using bitcoin to be technically correct. You aren't transferring anything, you are just changing numbers on the screen like the card companies do when you buy something.
Actually Starbucks is probably a good counterpoint to what you're saying here, if you're okay with not accepting 100% of the customers. One, a lot of the customers would be accepted pretty easily by just installing an app on their smartphones. I know not everyone has smartphones, that's why I made the cavet above. Two, I don't know about all Starbucks, but my local Starbucks has free wifi already. That means that anyone with a laptop could also pay with bitcoin, regardless of whether or not they have a smartphone. And having been at Starbucks a lot lately, I can say that customers having a laptop or a smartphone would probably account for 90% of Starbucks' typical customers.
Sure, it's not as simple as whipping out a credit card to pay, but if they're okay with covering most of their existing customers, rather than all of them, Starbucks wouldn't need any bitcoin acceptance machines. It doesn't fix the having to wait 10 minutes problem, though. I suspect if bitcoin goes mainstream enough that retail companies are implementing it, some would make people wait the 10 minutes, and most would probably just accept the (relatively small) risk of a double spend.