This isn't about white lies. This is about purposeful, blatantly false things to manipulate witnesses/suspects into giving confessions. Often false confessions - the article lists as one of the law's justifications that in the cases they looked at, 34% of minors reported giving a false confession (50% for under 14), but the adult rate is 8%, which is still appallingly high - if any other profession had a "vital tool" that ruins incorrectly someone's life 1 in 12 times, there would be major outcry and regulation.