It's a matter of scale and economics. Every dollar cost reduction per unit is significant over the multiyear production cycle. The changes for cost reduction make the design process more complex and a Camry or any car is full of legacy features (the model designation is nearly 35 years old).

On top of that car companies are massive and capital intensive with all the lack of agility that requires...retooling a production line takes many years from design to cars at the dealer. The critical decisions about programming stack had to be made in the early 1980's when the first microprocessor based control systems appeared in automobiles.

Back then, automotive engineers and executives would have hardly predicted the software complexity that was on the horizon. It was state level actors who came up with Ada and Drakon...But those are money is no object and failure is not an option inspired. Toyota probably made money via their level of software quality...shutting down production for a year to get it right would have cost billions. It followed the bean counting and rode the tiger.