For me, the best articulation of why coding is so hard comes from a 2000 Joel Spolsky article [1]:

It’s harder to read code than to write it.

I continue to use that line to explain coding to non-coder friends. This article's author seems to understand that as well, but it's worth making explicit.

[1] https://www.joelonsoftware.com/2000/04/06/things-you-should-...