You're wrong that the same argument can be used on cars. Because one thing that we have with cars is lots and lots of real data from the field. We don't say that cars today are safer than cars from the 70s because we have a list of safety features. We can say it because we have actual accident statistics and casualty rates.
Yet even with cars, even with the fact that they have experienced designers, when you build a new car model and put it out, you don't always get it right. You don't know what you did wrong. Which is why we regularly see safety recalls issued on cars - even from the best companies - for everything from software updates to changing the floor mat.
Until you see a model in use in the real world you simply don't know. Even if you have experience on a related model, there is the possibility of something new going wrong. Something you would have never thought of. Like the gas pedal getting stuck on a floor mat.
You take into account everything you know about. You run every feasible test that you think is useful. You run tests in simulators, on isolated components, on the whole model. You review and double review your work. You set up safety checklists to verify everything on the spot. But until you actually see the accident data, you don't really know whether you missed something important.
This is true for cars. It is true for airplanes. It is true for rockets. But the critical differences are that rockets are inherently more dangerous, it isn't feasible to do the same number of tests on them, and we don't get nearly as much accident data.
Option 1: Ride in a car with a single button labeled "press to start engines, you will not be able to stop until they run out of fuel". This car has been driven about a hundred times.
Option 2: Ride in a car with a "start engine" button and a "stop engine" button, plus a throttle. This car has been driven several times plus extensive testing on the ground.
"Option 2 is a safer setup" seems like a fair statement.
The shuttle also contains design compromises caused by congress splitting up contracting. E.g. The o-rings are there to seal connections that an ideal design wouldn't have. The pieces joined were assembled in different congressional districts.
Yet even with cars, even with the fact that they have experienced designers, when you build a new car model and put it out, you don't always get it right. You don't know what you did wrong. Which is why we regularly see safety recalls issued on cars - even from the best companies - for everything from software updates to changing the floor mat.
Until you see a model in use in the real world you simply don't know. Even if you have experience on a related model, there is the possibility of something new going wrong. Something you would have never thought of. Like the gas pedal getting stuck on a floor mat.
You take into account everything you know about. You run every feasible test that you think is useful. You run tests in simulators, on isolated components, on the whole model. You review and double review your work. You set up safety checklists to verify everything on the spot. But until you actually see the accident data, you don't really know whether you missed something important.
This is true for cars. It is true for airplanes. It is true for rockets. But the critical differences are that rockets are inherently more dangerous, it isn't feasible to do the same number of tests on them, and we don't get nearly as much accident data.