I see 2 problems here. One person went outside and shoveled oniy half the stairs. The person that did this, chose to do this, was most likely living behind the door on the side that was shoveled. First problem: Love your neighbor as yourself. We should help each other out. Second problem: when the snow melts the water will likely move laterally back, onto your side of the steps. Setting you up for a fall if it refreezes.