I get the impression that some government contracts are used as stealth subsidies. And SpaceX, Tesla, and Starlink have benefited from plenty of actual subsidies, too.

To be clear, I'm not implying that's a bad thing. These companies seem like an example of subsidies working as intended, i.e. driving innovation.

Can you give specific examples? Diluting the meaning down to “the government is also one of this company’s customers” just makes it meaningless. That will cover nearly every large company.