I tried doing the math and I don't know how the landscaping companies are profitable. The company maintaining my neighbors yards basic package is $500 per month. That includes weekly mowing during mowing season, aerating, testing, fertilizing, weed control, overseeding as necessary. Doing it myself, each application of fertilizer, preemergent, and seeds costs about $400 not including labor.
My guess is all of that basic package is a loss leader and they make money on actual landscaping, hardscaping, and services like tree removal and pruning. Or maybe they are getting all the chemicals and seeds at a much cheaper price than I can.