Today I was using Apple’s Image Capture to scan in some full-page documents. When I opened Image Capture the overview looked perfect but the scan button was grayed out and disabled. Changing settings and trashing preference files didn’t help. Even re-installing the driver software for my scanner didn’t help. What ever I tried, that scan button just stayed grayed out!

I couldn’t figure out how to enable Image Capture’s scan button, but I eventually discovered (after about 20 minutes of failed troubleshooting, and a little help from Google) that before the scan button will be enabled, you must select which area of the overview you would like to scan by dragging over the preview.

It was a bit of a facepalm moment, but I’m obviously not alone in finding it confusing, as there were plenty of people in the same situation as me on Google.
It seems obvious to me that the default behaviour should be to enable the scan button so that you can scan the whole document. It should only be necessary to drag a selection area over the preview if you wish to crop the document!
I really think Apple should rework Image Capture, it just isn’t up to their usual standards.
I once spent a long afternoon scanning in my family’s old photo albums. I scanned well over 1,000 photos and although it does remember the selection area you previously chose, there is no keyboard shortcut for that scan button so I had to use the mouse to click the scan button for every single one. It gets very tedious after a while!
If they were to make the default an entire document scan, and not grey out the scan button, then they could also assign a keyboard shortcut to the scan button.