I need someone to do a specific set of tasks, but there’s also a wider group of tasks which I’d like someone to do, but it isn’t urgent.
The posting goes out for the task we NEED. If someone more senior applies, and they can do more than the role needs, we pay them more.
There is no (and I feel comfortable with this absolute) scenario where you need to keep the salary range hidden, or where a published salary range prevents you from hiring a candidate for an expanded role. None.
The only thing transparent pricing does is result in an informed participant in the market, which is pricing signals and thus something Capitalism.
Once you go down the route of asking for special exemption to make your business work in an open market, you're not doing Capitalism anymore.
To be honest, the places I’ve worked for that could do this were not the best jobs I’ve had. That flexibility can sometimes point to other organizational issues.