Phobias are tough to break if you have one.
People, and just about all mammals often have phobias related to snakes, spiders (or all bugs), prey animals (just try roaring at a toddler), or any animal (fear of cats/dogs), and heights, etc...
A lot of the phobic response is hardwired. We evolved it to stay alive and not be the species that went extinct because we thought it was fun to play with snakes.
I have a phobia of drops. The weightlessness sends signals through my body that I'm "falling" and the body panics to get me to do something about it. I'm getting better at drops, tho. I've graduated to family coasters!
And as I mentioned above, I thought it funny that not just children, but grown adults absolutely shrieked in fear at ITTBAB's drop of incredibly fake spiders. Incredibly. Fake. And yet, the screams.
Likewise I can go through a haunted house with people jumping out at who are carrying running chain saws (minus the chain), and be completely unfazed. Meanwhile others lose their... stuff.
So, it's not about being tough. Sure in the "old days" children were raised in environments that habituated them to certain stimuli that modern folks are phobic to. But I'd like to see how a Dickensian waif would respond to a four story drop on a coaster.