Lab testing in the cannabis industry has been an evolving thing. The first time I heard of lab testing was when my uncle went to Amsterdam, and he purchased cannabis. The retailer claimed he had multiple strains testing at 35% THC or higher. It wasn't until I talked to a testing lab in Colorado years later that I was able to confirm that those levels in Amsterdam were false.
The testing lab in Colorado explained that testing technology previously used was very inaccurate, and that current technology is getting results closer to the correct amounts. They were quick to say that even today's technology isn't always 100% accurate. The issue of inaccurate results is compounded by the fact that not all testing labs are created equal. Many testing labs are run by non-qualified people that just bought a low quality spectrometer and set up shop. there's a big difference between simply testing cannabis, and testing it correctly with quality equipment.
Per MMJ Business Daily:
"Lab owners and policymakers believe that the inconsistencies will be eliminated by the state's recreational market, since rules will require mandatory testing. But developing regulations and standards for cannabis testing is a complicated task, and it's unclear how it will all play out.
Cannabis experts blamed the inconsistencies on several factors, including the genetics and age of the plants. Human error could have also played a factor, they said, as could have mislabeling and fraudulent marketing."
when you purchase cannabis, take the test results with a grain of salt. Just because it's been tested doesn't mean it's been tested properly. Because legit testing companies are poor at branding, there is no 'top testing company' in most areas that customers can demand when they walk into a dispensary or retail store. Hopefully that changes soon.