The software development timeline is slaved to the rigid manufacturing timeline. There is no allowance for slippage, so making things work By Any Means Necessary is the rule of the day. Concurrency problems often are not debugged; locks and similar are just sprinkled around until they disappear in testing. It is TDD taken to an extreme -- passing the enumerated tests, technically, is the definition of done even if the code is obviously poor or broken.
There are a vast number of software and hardware components sourced from myriad vendors that are swapped out every year to save a few dollars or deal with a supply chain issue. There is no stable baseline but all of these components need to work together. The code has to constantly adapt to the reality that someone sourced parts for a new model year that work differently or are in a different programming language.
This code is usually required to be supported for 10+ years. The developers don't just have this year's tech stack and code base to deliver on a rigid schedule, they are required to maintain several older implementations concurrently, often built in different languages and architectures.
Basically, the automotive industry has failed badly at the transition from being hardware manufacturing companies to being hardware + software manufacturing companies, and try to run their software processes the same way they ran their traditional hardware processes. Choice of programming language is the least of their concerns, that isn't the source of their code quality issues.