I believe that the majority of the users are trained to ignore g-mail spam since it's been working good enough for most people. Unless we condition the customer to always view the spam folder it's asking them to do something on top of already checking their e-mail.

My mother would just simply ignore the spam and often times spam catches majority of the phishing e-mails too. So it's a double edge sword educating and conditioning the users to review the spam folder. Why is it the end user's job to determine what is spam and what is legitimate ?