Unless you look out of the window to see who made the noise (the blind was parted, suggesting this happened), and the person you see out there was somebody that you know and trust.
I think they did open the door, either because they saw somebody they trusted out there or they simply waited a while after the noise and thought the person had gone. I think the more likely scenario is that they felt safe because they knew the person.
That's the wrong window to look out though
And if a person is known there's no reason to make a fake noise by breaking things. Just tap on Susie's window .