The largest number of people I could find affected by sight loss in the UK was 4.1 million by 2050, which is obviously far larger than the current number--and sight loss doesn't mean they can't read a paper menu in many cases[1]. The population of the UK is just over 68 million[2].
So two posts ago you were extolling the virtues of accessibility for at most 6% of UK's population, but now it's suddenly no big deal that 18% of the UK's population can't access your menu. And that's ignoring folks like my father: he technically has a smart phone, but he never has it on him and he wouldn't know how to scan a QR code even if he did have his smart phone on him.
And sure, nobody is turning away people without smart phones or blind people. Anyone is welcome to order food as long as they can figure out what your restaurant actually makes.
[1] https://www.rnib.org.uk/nb-online/eye-health-statistics
[2] https://en.wikipedia.org/wiki/Demography_of_the_United_Kingd...
EDIT: You also completely ignored my point about having a working ad-free QR reader installed. I've got an entry-level Samsung phone, which did not come with a built-in QR code reader. The free one I downloaded came with ads.