> If it's an advantage to them, then why aren't they doing it anyway?

Because it does not sufficiently offset the advantage they get from withholding pay information from labor sellers.

As soon as it does help employers more than it hurts them, they do advertise pay. Now that labor supply has shifted so drastically that restaurants and retailers have to close early, those places are advertising pay.

The purpose of the legislation is not to help employers, it is to help employees, who are at a disadvantage due to lack of information among other things.

> I've seen this with companies like ThoughtBot and GitLab that make a big deal out of pay transparency... problem is they're being transparent about how bad their pay is.

Their pay is bad to you. Maybe it is acceptable to someone else. Maybe someone is earning $20 as a bus driver and wants to switch jobs. Maybe they would be willing to work for ThoughtBot and Gitlab’s wages and work to become qualified.

Or maybe their pay is objectively too low and they will eventually go out of business. Either way, price transparency always leads to better resource allocation and better functioning marketplaces. Letting either buyers or sellers have long term disproportionate advantages is not in society’s best interest.