There is a huge difference here. Cars clock billions of hours of operation in an uncontrolled environment. These must deal with decades of use, abuse, neglect, sabotage, third party parts, etc. Anything that can happen WILL happen in a car.
Compared to this, rockets are tightly controlled environment and running for a very short time. There is also incredible amount of redundancy and supervision in a rocket but you will not be able to have double of every critical component in a car and then have separate controller to check if both are returning matching results and which might be faulty and you will not have a team of specialists obsessing every time something did not work exactly right.
Compared to this, rockets are tightly controlled environment and running for a very short time. There is also incredible amount of redundancy and supervision in a rocket but you will not be able to have double of every critical component in a car and then have separate controller to check if both are returning matching results and which might be faulty and you will not have a team of specialists obsessing every time something did not work exactly right.