Comment by plorntus

As far as I am aware though (and it depends on their contract/rules etc of course) that is completely fine and allowed?

Salaries are only secret if the person receiving it wants it to be. People should be able to say how much they earn without retribution. There is literally nothing wrong with it and it doesn't mean that they are going to broadcast actual company secrets.

If its a big deal for the employer then they should have put it in their contract/NDA and made that clear prior to employing them (but as I understand it that is illegal in a lot of places for good reason).