I think they're talking about proving your identity to a non govt entity. A few things that come to mind are any platform with a KYC, they require you to upload your ID and assure you they're secure with a little lock icon.
When I needed to get my newborn daughter's social security card I went to the local SS office, only to be turned away because I did not have an appointment. So I went home, finally got an appointment after an hour on the phone, trying to explain why I didn't have her SS card (apparently "it never arrived" did not compute), went back the next day with my passport card to provide as proof of identity. Only for them to say "we don't accept passport cards as ID. We can use your license though!"