Even people who have no overt fear (not to say panic) in their reactions to snakes, who kind of like snakes and find them interesting - like me - react differently to a glimpse of something that might be a snake than they do to actually dangerous things that are definitely not snakes but share basic shape - like live electrical wires.
People who have been "bitten" by live wires, actually hurt by them, actually at risk from their presence, do not commonly break out in a cold sweat at the mere sight of them. People will do things around live wires that they will not do in the presence of a two foot long garter snake in their back yard. People generally are neither fascinated or panicked by live wires.
Over a million years of evolutionary time, until maybe a few hundred years ago, snakes have been major causes of hominid mortality throughout almost the entire range of the species. They still are, in most places. It's dramatic - perfectly healthy young and strong human beings (at prime reproductive age, we Darwinians note) dead in a day or two, or losing limbs and crippled up, suffering greatly. It's memorable. And an ingrained fear of snakes is an important protection against this otherwise common fate - this is not something best learned by casual and surprising experience.
In conversation with immigrants from Central and South America, I have asked them what they find most startling about Northerners visiting their home towns - a very common feature of their response is a bemused description of the naivety of these visitors to snake country. They will step over logs and rocks in a Guatemalan jungle without even checking the other side, for example - just walk right on down the trail. Now we know a good share of these people are in fact prone to panic reactions if they do see a snake - but they don't have the culturally inculcated wariness. They don't fear snakes enough. So the ingrained flinch panic seems to be not a genuine fear of real snakes but an evolutionarily preset priming, an ingrained ability to develop the proper caution and ever-present wariness with little experience, a fore-shortened learning curve.
In the parks and natural areas I frequent two official notices to visitors are common: 1) The snakes here are both valuable and harmless, cannot hurt your children, are not occasions for panic and killing, please don't kill them. 2) Moose are dangerous animals - do not befriend the cute moose you run into, do not try to pet them, do not bring your children near them for pictures.
The same people who try to pose their children sitting on bison, will run their kids into the car and break out a handgun to shoot a bull snake that wanders into camp. This has no explanation in reasonable learning from experience and custom.