It is a general indirect method to measure it because of the fact that energy/GDP, it can be used in the case of busting miners and weed planters of course, but then they often use-
thermal cameras from helicopters and checking for electricity spikes in the grid, but what I describe is a tool economists use to estimate the size of the informal economy as a whole.
so they look at all energy production in a country, divide by GDP and compare it to what? and expected energy/GDP?
