You're generalizing a very specific problem
Of course German companies are not only hiring students. In general during the pandemic many employers stopped or postponed hiring, but as it cannot be avoided forever new job posting are starting to show up.
Jobs for autonomous driving are a special topic. While German automobile companies somewhat participated in the research, they were never as much invested as in other countries and are struggling now. Also many German companies missed the digitalization trend and are lacking IT skills. Because of that autonomous driving software is often developed with a IT partner company. Therefore you might want to search for those jobs in IT industry instead.
Besides that many German automobile companies have problems to switch to electric engines, and car sales went down dramatically during the pandemic, which led to hiring freezes that will not automatically end with the pandemic.
Students are still hired, because they are cheap and there is no long time commitment.