I think even public companies often disclose the prices though, especially for major ones. This being said, I have been thinking about the GitLab IPO, including things like fixing Reg FD for a while now.

..because financials is something people hope a company to be more open. It takes quite alot of courage to honestly reveal all the salaries. Then you wouldn't need a calculator anymore. So probably you should consider when you are acquiring talent, talent may set the price based on their own needs and have a right to negotiate. You shouldn't first of all, build an annoyingly outdated calculator and give it to HR to reject good talent and rely on community to mess up when the decision to build that calculator was mostly to serve company's own purpose. (which probably why its more biased to downpaying employees)