That’s true, however a properly engineered safety-critical system provides separation between assurance levels, so you don’t need to have the same level of assurance for the infotainment system software that you do for safety-critical displays and controls.

The FAA has historically done a good job on this front with aviation (notwithstanding the 747 MAX debacle, which was a failure implicating flight control software but not a failure of separation of assurance levels). Automotive software and standards and NHTSA is far behind on this front. Cost is certainly a factor; it is not economical to apply aviation safety and engineering standards and processes directly to automobiles. But in the meantime, it is an absolute Wild West for any contemporary drive-by-wire car.