Well, I wouldn't be quite so denigrating to the border officers - but I can certainly say that the CBP are terrible at their stamping, at least if you're entering using ESTA/VWP. They select a random page, a random angle, and a random location - except for the one time I had a canadian side-trip, in which case both stamps with the same exit-date were on the same page. (Currently using a Visa, they stamp on the page opposite the Visa - I'm not quite sure what will happen once that page is full. Yes, I have GE, but my Visa requires manual verification so I still get stamped every time.)
CBSA at least seem to look for a page with some form of stamp already on it. Schengen agents in general seem to get their stamps nicely aligned, and I've seen some nice "complete" stamped pages (3 visits, 2 stamps each time) in my friend's passports.
SIN were the only people who looked for the first page closest to the photo page, which tbh should be the standard since then your passport fills up as needed, with empty pages all at one end.