Cars and tractor PCB's as far as I'm aware tap into the vehicle's electrical subsystem, therefore living off the battery. This is why if you don't drive a vehicle or use a tractor regularly, you should be keeping the battery on a maintainer. Most control units have parasitic load to retain ECU state between engine on states, and to keep vehicle security systems doing their thing. They don't usually have dedicated batteries beyond maybe a button for cmos, but again, I haven't seen that in an automotive context. That'll flatline a lead acid battery if you don't drive it or run it for a couple weeks. Guess how I know?
Now, a lot of cars increasingly DO have dedicated antennas for OTA updates, phoning home telemetry and things like that. There might be some wireless CANBUS(It's either that or CAN, I don't have it on the top of my head at the moment).
The real culprit for me is bloody tablets and laptops. No excuses. The ultra-thin form factors are nothing but regressions in maintainability to me. Smartphones I don't even grudgingly accept anymore. The material selection and designs have biased only achieving realistic resilience through off loading that facet of design to accessory manufacturers. Anybody with a "naked" handset should know that current marketing/consumer quality metrics are not aligned on durability in normal chaotic human usage at all.
And if it's truly about waterproofing, the companies better include water damage in their measly warranties.