No doubt genetics and environment play a role in it but I think lights have made the biggest difference for me.  When I switched from LED's to HID a couple of years ago there was a noticeable difference in bud density and then 2 grows ago I switched back to a higher end LED's my buds are like rocks now. I changed the way I cure to and that may be part of it, I cure in buckets with an air pump on a timer and keep them in the buckets changing the air/burping once a day for a month or more.

I also think since commercial growers grow in such a large volume they can be picky about what goes out as flower and what goes out as a pre-roll or edibles. Personally I have not smoked anything from a dispensary that impressed me.