Diesel fuel is taxed lower primarily because it’s historically been the fuel for trucks. Using Diesel engines in cars is a comparatively new development.
“Taxing the fuel used by companies is hurting the economy more than taxing the fuel used by personal cars".
It's exactly the same reasoning/lobbying outcome that was behind the American (and now historic, I think?) tax advantage of light trucks over sedans. Both then lead to comparable, and in different ways unecological adaptations: diesels in Europe, F-150s stateside.
They are two different use cases. You need fossil fuel road transport from distribution centers and to the last mile of businesses and homes. I don't think electric will be able to handle that duty yet, and maybe not possibly unless for relatively short distance last-mile stuff.
