I've never used any of the pay-by-phone methods, although I see plenty of people do it and it does seem to take a bit longer than contactless card - because whatever unlock method you use, you have to unlock your phone (face recognition, finger print or whatever), whereas a contactless card is ready to go as soon as it's out of your wallet, so one less action.
I don't particularly have anything against pay-by-phone, just haven't yet had a need for it.
But I agree with the comments about people to whom it comes as a constant surprise that they have to pay for the shopping - on a similar note I worked at a chip shop at weekends when I was in college, and an amazing number of people would queue for ages before their order was taken, then once they were at the front of the queue, only then would they start scanning the price list to decide what they wanted.
Equally amazing was the proportion of people who would spend what seemed like ages trying to decide what to have, then order exactly the same thing they'd ordered for the previous ten Saturdays.