I've been on both sides of this, as employer and employee.
Salaries are arbitrary; it is what an employer values you as an employee, and what you value yourself at.
The best time to talk about salaries is when the company has offered you the role. Before then you have limited power. The reason companies set salary ranges is to frame the conversation on their terms.
> If they put $100K, they started first, so an employee who would have taken $80K now gets $100K.
This broadly assumes companies are not able to appropriately understand market salaries. I've never found this to be the case (certainly in large companies).
Large companies will have a salary range. But they will definitely also not want to publish them, for hopefully obvious reasons ("what do you mean my job title is on the market for $10K more??"). Its the same reason your contract probably says something about not revealing salary/renumeration.
I stand by my thesis; jobs with salary ranges I've always had more trouble negotiating. Where jobs without salary ranges I've found myself earning 10-15% more than peers. I'd argue the problem is that employees undervalue themselves and are risk averse in negotiating ("If I ask too much they will not hire me").