Yes, the government can trace people right now, if people are not protecting their identity. Because there is no ubiquitous ID, it is still possible for you to protect your identity in almost every part of society. But that possibility will rapidly disappear when a ubiquitous ID arrives.
The difference between rounding up people or not is often just whether it is logistically feasible. Right now, even if they collect every kind of data from every business, it would be a nightmare to attempt to collate it all, because it comes in so many sources with so many differing fields that may be out of date or inaccurate or wrong and would have to be normalized etc etc etc. Impractical to do on a very large scale. Except when there's a single identifier they could look for, which would completely solve the problem for them, and make it easy to round people up.
Companies that sell data to the government without the consent of the public is a huge problem we need to deal with, for obvious constitutional reasons (4th amendment).
The difference between rounding up people or not is often just whether it is logistically feasible. Right now, even if they collect every kind of data from every business, it would be a nightmare to attempt to collate it all, because it comes in so many sources with so many differing fields that may be out of date or inaccurate or wrong and would have to be normalized etc etc etc. Impractical to do on a very large scale. Except when there's a single identifier they could look for, which would completely solve the problem for them, and make it easy to round people up.
Companies that sell data to the government without the consent of the public is a huge problem we need to deal with, for obvious constitutional reasons (4th amendment).