My grandma lost her vision when she was young. Even before capacitive buttons, buttons were very hard to find by touch. It has been an issue for more then a decade.

Off topic, but a lifehack for those who have visually impaired loved ones: we use glass paint contour paste on the center of buttons. It's basically used in glass paintings to stop paint sliding from the glass, so it can make a good noticeable bump or line. But – it only works on hard surfaces and if the buttons themselves are not very sensitive.

If you can lightly brush the button while you are "looking" for bumps, then it works.