That's the point, you never have any grounds to demand more unless you have another job offer on the table. When companies say they can't afford to pay you x,

That's the point, you never have any grounds to demand more unless you have another job offer on the table. When companies say they can't afford to pay you x, they mean they don't want to pay you x. Yes, sure, perhaps the employee was being cheated, but pay transparency is not going to fix that, that just insures everybody is being cheated evenly. The cheating happens when the profits of the company are not distributed to the people that run it, but to the people who own it.