Go check out VxWorks or the like. only 20K a seat, build tools at a similar price, and then oh joy, runtime licenses required to deploy the sw you wrote.

Which are reasonable prices when lives are at risk.

Yes, I know RTOS are not general purpose, this is NOT apples to apples, but that is what that kind of reliability, testing, safety certification, etc. costs.

Or QNX for the price of Windows, for a certified UNIX.