If 70-80% of people have had coldsores, how come genital hsv 1 is not more common?

Not so easy to pass: Nowhere near 70-80% of all people (in North America) have had cold sores. By age 40, around half of all adults have positive blood tests for HSV1. Probably about 20-25% of them have had overt oral herpes outbreaks, i.e cold sores. Why not more genital HSV1? Because in oral sex, when the oral partner has HSV1, transmission occurs infrequently -- as a guess, about once for every 1,000 exposures.