This seems like a stupidly conspicuous location to setup a meth lab unless you assume that not a single person visits the facility for months at a time and no one would notice large plumes of smoke rising from it.
No disagreement from me. However, we are talking about tweekers & cookers. They tend to be genuinely resourceful, yet not the most intelligent of peoples.
It took 2 years to get a blatant lab shut down on my upper middle-class street. Ex-neighbor's ex-engine mate happened to transfer from FD to our local PD precinct & made detective. He was the only reason the rat nest was disturbed.