I'll tell you where the fear comes from. Like you said, there's movies / media and also social input.(example, family is afraid of snakes and it rubs off on you)

Most very young children are fearless and even curious of snakes. It's only after years of subconscious "programming" and or negative experiences with snakes, that people become afraid of them. In most cases, people who are terrified of snakes were brainwashed into it subconsciously, or they were flat out taught to be afraid of them which is useful in parts of the world where deadly snakes are everywhere, but not here, not useful when we're talking about garter snakes.

We are not born afraid of them. It's a learned/subconsciously acquired fear. Shows like animal planet are definitely not helping matters.