Many modern ford cars have 6 CAN buses. ICE cars are not simpler. The tech _has_ been beaten with the hammer of incremental improvement for a long time, but ICE cars are not less computer controlled. If anything ice engines require many more "computers" and sensors to be efficient

My Hybrid F-150 is so freaking complex. They basically seem to have swapped many components over to electrical drive (like the F-150 Lightning), but they still have to slap all of the ICE components in there as well.