A bit of a nitpick, but ROS is not an OS, it is a middleware. Who knows, maybe somebody makes a ROS adaptation for a hard-realtime POSIX OS, would be totally possible.

Though I agree, ROS is nowhere near the stability level needed by industrial and automotive products. It's great for prototyping, but one has to keep in mind the inevitable refactoring of the communication layer, and keep the core functionality ROS-independent.

Nvidia drive PX2 uses QNX, I think for an open source solution someone should try to figure out a solution with sel4 running on RISC-V so there could be a full proof that the system supports hard realtime.

So is making a car so hard to work on that it has to go back to the dealership just to change out a dead bulb.

Definitely on the roadmap. See ghs.com.