Citation needed. AFAIK they sometimes result in a profit (as with GM in 2008) which unsurprisingly gets attention. But the long history of postwar nationalization’s in Europe and the US are not promising by this metric.

There are other reasons, some good, for doing so. Amtrak, for example, might better have been formed as a nationally operated part of the transit network rather than as a quasi-private-sector corporation that is neither fish nor fowl and suffers for it. Municipal utilities often work quite well at least here in Northern California, though at the national level I only know of the TVA and the western dam systems.