Fair points to say the least. Also had a bit more of a think on it, and realized that the [FONT=Tahoma, Verdana, Helvetica, Arial] other issue is that the cost of maintaining gps accuracy through differential gps is costly.
Even with d-gps you get accuracy within 10cm. I dont know about everyone else, but I would get super pissed off by a 10cm strip of lawn that wasn't cut....[/FONT]
To be honest you could lay an underground sensor around the perimeter of the lawn easily - just a wire that a sensor on the mower can identify. That would be cheap and easy. I was a gardener for years and objects in the grass would be a major problem liability and otherwise. That and the power needed to ensure the grass shoot never clogs - definitely need to improve on the clogging and then there's the emptying of the bag. If no bag then you are back to increased liability for potential projectiles, all the ones that are typically caught in a bag.
As for an online business I still believe someone could make a serious run at the social media aspect of catching fugitives like what I put in a thread the other day.
http://www.wickedfire.com/shooting-shit/155001-social-media-big-brother-rewards-profit.html
The ad dollars would dwarf the reward money.