You've thought this through, and I don't mean to detract from your point. Something else to consider - photo-aging is real, and is easy and quicker to observe than skin cancer. It's a cumulative effect, and by the time someone's in their 30s, their relationship with sun and sunscreen shows.
I know. I once saw an interview with a women in California in her late 20s I think, who got kidnapped when she was a child and barely left the house for years. She looked so young because of her skin.
I'm aware and do it in moderation. I usually wear a hat to protect my head and part of my face. Also where I live (New England) the sun is not as strong as in some other places.
