I am not saying people are dim for "falling for intentionally malicious design", because I do not see what is intentionally malicious -- that word has a meaning. It is not malicious. It might be unclear; I'm not convinced it is even misleading.
I am saying I do not understand why people don't grasp that "annual plan, billed monthly" means something priced yearly but paid for in monthly pieces.
Not that I think they are dim, but I do want to understand what the comprehension gap is here.
After reading many replies I think that if people are saying that "annual plan" is too ambiguous for anyone with a credit card, then "yearly, billed in monthly instalments after free trial" should do the job. But then I expect we will still see people expecting this means they can cancel after a month. Because the thing is if they say "one year commitment, billed in monthly instalments" that is actually untrue; you can in fact get out before a year is out, it just costs you an early closing penalty.
(I _am_ saying they are dim if they are expecting to game it by cancelling after a month.)