Governments are always looking for better ways to track (and control) their subjects. The idea of a national ID[1] has been floated by various US politicians since before it would have been digital. Many Americans oppose it because they fear a government using it to round up dissenting citizens, and others oppose it because they fear it would be used to more effectively identify illegals (some oppose it on both grounds), so between them it's never gotten started.

The UK government does seem especially keen on the idea of a digital/video dystopia, though. Weird, like they're trying to prove Orwell right.

[1] Social Security numbers aren't unique and you aren't required to carry your SS card, so it doesn't work for that purpose.