Mark Perry has done a great service by applying this principle to energy. In "Inconvenient energy fact: It takes 79 solar workers to produce same amount of electric power as one coal worker," he writes:
To start, despite a huge workforce of almost 400,000 solar workers (about 20 percent of electric power payrolls in 2016), that sector produced an insignificant share, less than 1 percent, of the electric power generated in the United States last year (EIA data here). And that's a lot of solar workers: about the same as the combined number of employees working at Exxon Mobil, Chevron, Apple, Johnson & Johnson, Microsoft, Pfizer, Ford Motor Company and Procter & Gamble.
In contrast, it took about the same number of natural gas workers (398,235) last year to produce more than one-third of U.S. electric power, or 37 times more electricity than solar's minuscule share of 0.90 percent. And with only 160,000 coal workers (less than half the number of workers in either solar or gas), that sector produced nearly one-third (almost as much as gas) of U.S. electricity last year.
Of course, to do a complete analysis, one would want to look at capital and other costs, not just labor costs. But given the overwhelming data on labor, it's hard to believe that other costs for solar would be so much lower as to make solar less expensive. And we don't have to speculate. If solar power weren't more expensive, governments wouldn't need to subsidize and regulate so heavily to get people to use it.