Chrysler was 1979, GM was 2008 totally different political economic climate. In 1979 ordinary businesses and unions had a huge amount of political clout. And Chrysler wasn't an ordinary business.

By 2008 only Wall Street investment banks had that clout. That's because under neo-liberalism the profits from the real economy are funneled through the investment house. Letting them go under means the spigot gets turned off.