[1Old Pro]

Then a few short years later the hippies were wearing jeans they’d purposely ripped the knees out of. What a change.

I have a different recollection of the torn jean look. During the 70's I had numerous jeans rip at the knew due to wear and washings. I think it's today's impatient youth who buy pre-ripped jeans.

[Gen.Blather]

To rip your jeans naturally at the knee requires that you work. Less of the seventies and eighties kids actually worked. Thus, the market for pre-ripped jeans.