Looks completely out of context. Undisclosed income is black money. You pay taxes on salary/income (most of which is deducted at source). The state does and will almost always know your salary/income, period.
Even the most determined defenders of taxes usually concede that they have downsides. It's entirely reasonable to propose limits on what the State should do with tax information. As a hyperbolic (but real) example, the State also usually has access to single transactions from your friendly neighborhood sex shop.
But that does not address why the government should then broadcast that information. Obviously an income tax requires the government to know your salary, but why should it become a public record?
Because free flow of information makes free markets operate better.