Ah, that's the author flattering the reader. If the author had picked a genuinely tricky example for the first one it would have turned many readers off.

Of course a question like the old bat and ball one is ridiculously simple, after you've been warned that many people get it wrong and hence that you should probably stop and think for a few seconds before blurting out the first answer that pops into your head. Do it without that warning and it's easier to get it wrong.