I'm going to give some negativity. As an Englishman, this is a ridiculously impractical idea.
If you have to remove a card from your wallet to make a payment, just do it! There are indeed the same amount of steps to making an apple pay transaction than a normal debit card! It takes roughly 10 seconds to pay by card. It works, just stick with it, or pay by cash.
I'm not sure on the legal implications, but using it whilst driving would be illegal here too. That and you look like a major idiot using your phone to pay for something.
iPhone will be able to wipe your arse next... And it will make a **** job of that too.