I think it was meant in the sense that it has (mostly) a single source of information. A big part of safety critical systems is having redundancy and often vot

I think it was meant in the sense that it has (mostly) a single source of information. A big part of safety critical systems is having redundancy and often voting systems, or sensor fusion. So having a single source of information means that you can potentially go down with a single-fault condition. (e.g. If your vision system is in the visible spectrum, things like sun glare, snow, bird poops on your lense/windshield, one of your cameras fails and you lose stereo vision etc)