It's not just mental, as you age you lose moisture in your skin and with that accuracy with touch devices.

Hmm, would explain that frustrated pokey interaction I see elder people often throw at touchscreens... you know, chin up, peering down through their reading glasses, going for a 4th, 5th try at something...

Is that what's going on? So many touch gestures seem to rely on landing in the right 2mm diameter area, but the minimum reliable resolution for touch seems to be a 4mm diameter circle. It's even worse for my father, even though cognitively, he would have no trouble understanding the hypothetical requirement. It's also noticeably worse during the depths of winter.