That's interesting; is it your perspective that people generally believe "that which is commonly done" to be equivalent with "that which is probably harmless"?

I don't see it that way at all, but my attitude about risk doesn't fit well with what I see in the culture where I live; perhaps the people I'm observing experience the world more in the fashion you describe.

it's a pretty normal and established occurrence I'd Say. I don't know if most people do that, but yes one way to rationalize or reassure yourself that what you are doing is safe is to look around at the wider group and see if people are doing it without worry.