Why do we still use the PPD? And give liver toxic drugs because of it?

To step foot in a hospital, you need a PPD. But why? We have a vastly superior test (the Quantiferon) for one. But also, the PPD is a pretty crappy test given its complications. We have the BCG cohort who all seem to magically have gotten TB and should be handed a liver toxic drug because their PPD vaguely read 1mm over debatable cutoffs. Anyone who isn't an ID doc seems to strongly defend whereas the ID docs will point out the high risk of false positives. My point being, why can't we... Why do we still use the PPD? And give liver toxic drugs because of it?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums