why is it 'culturally' OK to wear helmets on a wooden vert ramp but not giant hand rails or even concrete bowls?
This may be more obvious than I think but it's likely due to vert/bowl/park skating pre-dating (hardcore trick) street skating and the park owners navigating legal culpability by forcing those wishing to enjoy their park to wear, at least, a helmet.
Vert skaters were probably like, "Oh, that's wack" at first but, you know, them's the rules. Then they just got accustomed to it. Hard to worry about looking corny when everyone's forced to look corny.
Some of them are probably glad they get to wear a helmet without any stigma, like when my gf forces me to take a shower before I get into bed. I put up a fight at first and act all put out, grumble, but when I'm laying bed, clean as a whistle, I'm kinda glad she made me take the shower.
But street skaters were real rebels. Their whole shit is illegal. Nobody's telling them to do shit. To keep the analogy up, they don't have a bed to get into, showered or unshowered. No gf giving them an ultimatum. They sleep in the streets. Ironically, they probably sleep in a dry shower in a flop house.
But, yeah, nobody's telling them shit. Because property owners don't even want them on their property at all. Street skaters are running from the cops, they don't have the regiment of some old dude (who's nice enough but also doesn't want to lose this sweet skatepark business he's running in court) telling them, "No Helmet, No Skate".
They were never forced to get accustomed to it like the vert skaters (whose alternative was not skating at all).