I reckon they don't bust anywhere close to a significant percentage of grows. There's tons & tons of shitey, damp, badly grown stuff round here (I wouldn't smoke that shit though, I'd also rather pay more for better stuff) - all they'd have to do is get someone who actually knows what they're doing to grow the weed & all that shite stuff would be banging weed without much extra expense (other than the extra time taken to dry/cure it).
I read that somewhere as well. Must be a shite place to be in that's importing the damp vietnamese grown stuff lol. Or maybe they're exporting all the good stuff & leaving us the shite because they know we'll smoke it anyway.