I use a junky $5 calculator when I'm working with my mill and lathe. It's easier to have the little thing there at hand in the machine shop to do quick calculations than to have a whole computer.
As a habit, I do not touch others' phones. CoVid helped solidify this decision, but meeting a sex worker that also cleaned houses was the real eye-opener — she would casually go from cleaning a toilet to washing dishes to fluffing johns... then hop right back on her phone. In my previous career (as electrician) many crawlspace disasters were photographed on my own personal device.
Obviously no hand-washing was involved in the above observations. I personally no longer use a mobile phone. Hand sanitizer is my fragrance (I add witch hazel ... shh!)