Another use for ringing the bell is to see if anybody’s home. I’m going to guess that lack of response to the ringing caused the perp to assume that there was nobody home and that it was safe to kick in the side door.
We first check our security camera monitor. Anyone suspicious looking will not get a response at the door. We decide who we will respond to. Then if they try kicking in the door they'll meet Mr. Shotgun. Just saying, lack of a response don't mean no one is home.