Many jobs involve writing up notes or reports and all sorts of other things where 'office work' isn't seen as been a big part of the job.
Many, many people also volunteer or take part in hobbies or activities when things are written up AGMs are held, grant applications need to be completed.
Don't you ever write to companies - more generally now by e-mail rather than printing out as a letter.
I mean, I'm using my laptop now as I MN.
Then everyone who goes to University, or studies anything later in life.
I'd say it was more surprising to find people or working age who never use a keyboard