He had difficulty writing an address on an envelope.

This skill is something we expect of 8 year old children.

I sympathize strongly with the author. I write with a pen so infrequently (years between handwriting) that I often have handwriting errors that displease me.

So I usually do some practice writing on scratch paper before attempting the final version.

Notice he said "printing the address would have taken less time". That doesn't sound like the issue was formatting or knowledge. It reads to me as the physical skill of penmanship.

Nowadays, not really. I had a similar experience - the first (well, first in a few years) time I had to send mail was this year for my taxes, and I ended up having to buy another envelope from the post office because I mixed up the delivery address and return address.

Maybe we used to. When sending letters was still a thing people did.