I've certainly have many legitimate emails marked as SPAM by Gmail, that's why I have to check my SPAM folder from time to time, and why I am frustrated to receive to many SPAM email even though they are marked as SPAM.
These email are marked as SPAM but Gmail is still failing to detect them as phishing.
Providers also often hard-block emails when they are certain to be SPAM. Some people don't know it, but many SPAM emails sent to you are not even shown to you, not even in the SPAM folder.