I don't ask to be obtuse, it is relevant in that I'm trying in several ways to say that what we see on TV is not accurate in several different ways. It wasn't obvious to me until I got into more serious plate work either.
Your answer is correct except that to note crosses home plate is any touch of the edge of the white part, the black is not part of the plate. So the width of the zone is 17" plus two baseballs, I use 23 5/8" just for good margin. I can't see that 3/8" so I want to be sure. Its a question I use sometimes with coaches and parents that won't shut up, as fans we really think we know the rules but its mostly only high level. Unfortunately all the TV boxes are 17" which really skews the view, the ump score cards presentation etc. Our minds would do much better with a box where the the line is out and everything inside it is a strike, like the sideline in basketball.