I doubt they really meant all the testing was entirely manual. That's basically unheard of these days. But testing graphic UI software has its challenges. If you're creating software for a phone, a laptop, or a web browser, there's an entire industry of companies and tooling to support automated testing. Once you start running your user interface on a custom hardware platform in a hybrid real-time/android OS environment, you're off in unknown territory and probably have to build a lot test tooling yourself. If someone said that, they were probably talking about manual integration testing on the full vehicle platform, and not that every single part of the test process is manual.