varjag parent
Apollo project software was controlling the stages of Saturn V flight vehicle, orbital and lander modules, and ground systems. So no, it was not doing less than a family SUV Javacsript blob; certainly not 10x less. And most of the things it did were mission critical.
All isolated systems or sensors that simply notify humans or providing them with basic calculations. The MP3 and entertainment systems on modern cars are orders of magnitude more complex. Again, you don't have to take my word for it, just look at the memory available at the time.
Computers in Apollo programme controlled most of the function with minimal human involvement in the loop. The dynamic systems were orders of magnitude more complex than what you find in a modern vehicle.
Also I can assure you no-one at Cariad had to write an MP3 decoder. And speaking of sensor control, my car (on its 4th year now) still fails to unfold the mirrors once in a while.
We also have huge, orders of magnitude advances in tooling and process since mid-1960s. For starters you don't have to weave your program into magnetic core fabric by hand.