Chris,

I think its a question of never being aware in the first place.

I am currently refurbishing a wreck of a house and contracted a reputable small builder to replace floors in a Victorian house (was compacted earth overlaid with tiles).

He told me he had done similar work many times, I'm sure he was telling the truth.
On the day he laid the concrete I happened to be onsite.
I had a discussion with him about cement burns, he was aware cement could burn but viewed it as trivial. He had no idea they could be serious or life changing.

He was genuinely surprised and thanked me for explaining the risks.
Some might think he was just BS ing me, but I've been around a long while and if he was, he is a fine actor.