In the 60's and 70's all you got was leaves. $20.00 per ounce.
Now you get buds which have always had a much higher concentration of THC. People pay $75.00 for 1/4 ounce.
I really suspect this has more to do with larger crops and decreased bulk when smuggling the stuff than with a much higher THC content.
My observation is that people who smoke it just don't smoke nearly as much.
I think the difference is like that between beer and distilled spirits.
Just for the record, I do not indulge in either alcohol or pot.
This is a non issue.
"In the 60's and 70's all you got was leaves. $20.00 per ounce."
That may be all you got. I recall cheap "homegrown shake" being much more available back in the late seventies when I first tried pot, but hardly anyone would buy the stuff. It was crap somebody either found growing wild or that they tried to grow from seed from marijuana from the tropics that wouldn't mature in time before the first frost up here. It was 1978 the first time I smoked pot and what I smoked was powerful sinsemilla, seedless buds. Mostly what was around back then where I live was pretty good Columbian and weaker Mexican. As the years went on the Columbian supply dried up as they switched to cocaine and the Mexican got a little better. By the mid eighties prices and quality were about what they are now for Mexican. Prices for sinsemilla have gone up some but I'm not sure that the rise in price was met with a corresponding rise in quality. Today I'm told by my friends and by the narcotics officers I work with all the time that 90% or more of what is out there where I live is regular old Mexican going for between $25 and $40 dollars a quarter ounce depending on who you know. Ounces are between $80 and $100. Pounds go for around $1000. Sinsemilla can go for anywhere between $50 a quarter ounce on up to $120 a quarter ounce depending on quality, who people know, and how much people are willing to spend.