Design differences
Typically, established OEMs take a top-down approach to system design. In a top-down approach, the system is decomposed into subsystems, which are further subdivided into components. Each component is then custom designed to support specific vehicle characteristics and follow specific requirements, such as using a limited range of connectors from approved suppliers.
Startups have time and budget constraints that often do not allow for a top-down approach. Instead, engineering teams use bottom-up vehicle design. Engineering teams are instructed to use off-the-shelf parts that are best suited for the intended application. After that, the systems engineering and wiring teams were tasked with trying to piece all these pieces together to form the vehicle functions and make connections. Unfortunately, changing or customizing off-the-shelf parts is not possible without a major investment. This often results in some compromise, resulting in increased wiring required to integrate parts in the harness.