Hard to say why sometimes simple beep works, even from the cell phone (in restaurants) and other times I have to swipe.
I have always wondered why in the USA, I see so many people with their transparent iPhone cases in which they carry the credit card. Europeans do not do this.When I asked these people, I was told that there are many merchants in the U.S. who do not accept cell phone card, and so the physical plastic card must be used. I suspect all of this is in some setting of the merchant terminal.
I would still like to be asked for PIN when I use the plastic card for high amount. With the cellphone, the biometric keeps me calm. Anyway, thanks for all the information.