[evilelectron]

The rear view camera system almost always runs independent of the main Head Unit (HU) or In-Vehicle Infotainment (IVI). In most cases the rear view camera view is a single application specifically coded for the target micro processor (SuperH for example) and is the only thing running on that micro processor. The HU and the rear view camera share the display. While you are driving in R the HU is booting Linux or QNX and when you move to D the screen switches to the HU. The rear view camera application keeps running uninterrupted.

[numpad0]

What you said is/used to be right but GP is also probably right, hardware companies love to migrate distributed and reliable system into overcomplicated but integrated Linux contraptions