There must be more to it. German automakers did belong to the top 10 (for some periods even top 5) R&D spenders world-wide. It seems they just did not spend it wisely. Similarly, the claim they "kept wages down" seems to require some nuance. VW workers are known to be very well paid. From the outside it seems like these companies became large behemoths who were not able to spend their R&D money wisely and their outsized pay packages forcing them to offer their products at uncompetitive prices.
As a university computer scientist, I saw our graduates hardly getting job in automotive directly while mechanical engineers got all the good jobs for years. Then about 10 years ago the opposite happened: people quit their PhDs because industry was hiring as many CS /AI people they could get. Industry understood that they needed to invest (even it was already a bit late). However, they IMHO failed to turn scale that talent into sustainable innovation. Many people I know left again automotive. I think industry struggled quite a bit to translate engineering leadership to a digital age in many parts. I think it was easier for pure EV manufacturers to embrace also other digital innovations.