Several things: 1) Mass scale surveillance becomes trivial and you'll end up in a database of suspects even if you've never broken the law 2) Your identity can

Several things: 1) Mass scale surveillance becomes trivial and you'll end up in a database of suspects even if you've never broken the law 2) Your identity can be checked without your knowledge regardless of probable cause 3) The technology might not be safe, but this is much less of an issue than #1 and #2