It’s due to when you harvest the plant.
The longer you let the plant go, the more THC degrades into CBN which is what makes people relaxed. Sativas typically flower longer and take longer for the THC to degrade, so sativas typically lead to a creative high.
But it’s entirely down to harvest time, and yes there is a vast difference in the effects between THC and CBN. Cloudy trichomes = THC and Amber = CBN, let a plant go until it’s 100% amber and you won’t be moving after consuming.
So to answer OP find edibles that are fully THC and avoid CBN, or find some flower that’s not too amber and make your own. Thats kinda the only options, you don’t know what type of trichomes edibles are made from, some list the CBN quantity, but not all.
A more realistic metric would be used books (also reflects the quality of all but brand new fresh books which are a rarity obviously), but you can’t quantify that price, so yes using new is disingenuous, but go off on a rant I guess? I think it’s a great idea, but let’s not kid ourselves that people would actually be spending that amount on books. It’s great for a feel good story though, I’ll give you that.