Could this be the reason , It's like 15-20mn to get at least 1 confirmation if I'am correct ?
Anyway the point is that we need some time to get transactions verified , could this actually prevent us from going to mainstream ? I mean if you want to buy something from McDonald are you supposed to wait 15mn while that's the time of your launch break ?
When you are buying parking tickets are you also supposed to wait few minuts ?

It wouldn't make any sense .
Honestly , I'am not even sure what controls the speed of the transactions .
you are making a minor mistake about transaction speed and confirmation speed. the transaction speed is super fast in matter of seconds but the confirmation speed is longer (minutes).
businesses like McDonald (if they start accepting bitcoin) won't care about the confirmation as long as they see the transaction in their wallet. and in the hundreds of their customers i doubt if there would be even one or two who might scam them and double spend the bitcoin.