there is really no evidence to suggest that marijuana has more thc in it now than in the past. or that 'modern cultivation' techniques have somehow created super weed. the government likes to talk this up in order to convince ppl that its "not the same" as the stuff they (the politicians, judges, adults of today) smoked when they were younger, you know a way to make them feel better than they are locking people up for what they used to do.
The only difference is the weed in america in the past was just low quality. Sensi existed back then too...
The stuff I was smoking in the 70s... sticky hairy red bud and columbian was anything BUT low quality..... but I don't have anything to compare to. I do know it had some serious kick ass flavor to it.... that was almost as enjoyable as the getting high part. It was the kind of weed that two or three hits out of a bong was good for an intense buzz. I'd like to get some of that same stuff today.