Less than half of Americans have passports, and of the remaining half, a significant fraction do not have the necessary documents to obtain one. Many of these people are poor, people of color, or marginalized in other ways. Government ID is needed, but you generally find the GOP against actually building a robust, free, ubiquitous system because it would largely help Americans who vote Democratic. This is also why the GOP pushes Voter ID, but without providing any resources to ensure that Americans can get said ID.