Lawns are actually interesting because it wouldn't have to stop at mowing.

Lawncare involves a lot of well-defined tasks on a well-defined surface. A lawnmower bot could also have a hopper to dispense fertilizer and seed. In a more extreme, force-intensive form, it could even dispense topsoil or aerate.

In winter? Salt my driveway and sidewalk (assuming ploughing is out-of-scope for this particular robot).