I guess I could offer to pay them a monthly retainer (global payment) instead, but then they would have an incentive to not cut the grass often enough. Also, during the dry summer months when the grass doesn't grow, I would be paying them for nothing.
Or I could not have them on contract at all and call them when I need them, but they might not be available. Then, I would have to spend time shopping around to see who is available at that time.
Or I could buy a lawnmower and cut the grass myself, but then I would have to use time I'd rather spend refereeing soccer games or doing something else. Plus, I like the idea that I am helping to provide jobs in my community.
Or I could dig up the lawn and plant ground cover instead.