> the candidate is at a disadvantage... there are companies that collect salary info from companies, and employers use these databases to look up salary ranges.
Collectively we have the power to stop at least one of those sources of information cold and the other is limited to the amount that the employers are willing to part with (and employers are typically not all that happy to supply external recruiters with such information because it may backfire).
That's collusion and price fixing. Possibly even illegal in some places. Feel free to spell out the names of the companies involved, we may have a second hiring scandal on our hands if this is really true.