It was beyond the phone screen based matters you see (which is a great dirt magnet beyond toilet seats actually, like keyboards, coming from the need of constant touch in all and every life situations). I believe you hold paper menu without the need of smearing the matter on your skin all over it you know (or just leave alone on the table if it is one page), unlike touch screens where it is a must ... Also the fast food places stear people towards glass surfaces smearing the cover of their skin all over normally had no menus, just look up and say what you want. Now, you must touch all over like the handle of the public toilet, only more! Different scenario.

[1] https://ihpi.umich.edu/news/your-cell-phone-10-times-dirtier...