In what way should the gov decide which company to fund, and why? If it is a commercial/private company, their existence should be justified by their profits.

In what way should the gov decide which company to fund, and why? If it is a commercial/private company, their existence should be justified by their profits. It makes sense for the government to fund R&D that the private sector won't fund, possibly because it would be profitable for the overall economy but not for any one company. Obviously a dozen companies are already building self-driving so that doesn't apply.