for the vast majority of people an automobile is an appliance, one that they care for about as much as their toaster
I don't agree. A toaster can be abused and run into the ground without hurting your wallet too much. People tend to sit up and take notice when you start talking about dropping half their yearly net income on something. Now, that doesn't mean they have common sense -- plenty of people have all the sense of a turnip, but to suggest they put a car in the same category as a toaster is absurd.
As for those sensors... no, it takes more than one failed sensor to blow up your engine. There is an oil pressure sensor, and an oil level sensor, at minimum, in the vehicles you mention. But let's ignore that and say they both simply give up the digital ghost without warning... the car's onboard computer will still trip out when you exceed the odometer tracking the miles since last oil change. But even if all of that technology fails, there is still one thing left to save your engine from mechanical oblivion: Your own eyes and ears.
Engines that are low on oil tend to run hot, and they tend to run hard. They don't accelerate, they feel like they're losing power, and dear god do they make noise as they die. All that overheating metal is going rat-a-tak-tak and war-warrrrr-waaaaahhhhhrrrrr.... as it dies, smoking and belching steam. If you fail to notice all of these signs, you don't deserve a car.