The lawnmower may be happy. Before the faucet looked like it was higher than the wheels, but now the lawnmower can run into the box. And it is a much larger target.
Haven't seen curb feelers on a car in quite awhile. My grandfather used to have them on his '56 Mercury.
You could put a positive charged magnet on the hose bib and a positive magnet on each wheel of the mower. Have to be pretty large magnets to do any good. Make for good conversation pieces over the garden fence.
How about capacitance sensors and power steering on the wheels so when it senses it is near an obstacle, such as a box sticking out of the building, the wheels will steer it away from it.