Commercial work in general doesn't care about the capital costs, it's all about availability, efficiency and utilization. The internet says commercial mowing costs $30 to $150 per acre depending on size and location. The mowers being talked about mow about 10 acres an hour. If the operator is $30 per hour and the mowers burn a gallon to two an hour, the operating cost is a small fraction of the total cost. If you assume $50 an acre for mowing, you only have to mow less than 2000 acres to pay for the $80,000 mower. The mower is paid off in 200 hours of mowing.
It looks like a real bargain to me.