Is a company required to disclose salary for job posting?

A little background.

I have worked for this company for 5 years. A little over a year ago the owners of the company sold it to a larger company due to "being very profitable but unable to get out of debt". I obviously dont know much about this but the new company has been very shady lately and im looking for advice. I can't say what it is the company does (NDA and all that) but I'll give as much detail as I can and ask my question.

When I started with the company, base rate was around 17 bucks, which at the time was much better than minimum. Every year or so it would get a bump and we all got loyalty bonuses for 1 and 2 years respectively. I also got a promotion to a minor leading role which came with a dollar increase, then moved to a new role in a different department with the same pay for...reasons. Then this new company took over and things started changing despite their promises they wouldn't.

We lost our loyalty bonuses going forward, but were told the pay structure wouldn't change (those that had them, kept them) they didn't announce this until late last year, and some people that were entitled to that 1 or 2 year bump didnt get it, but others that started a week or two before them did.

Our benefits changed to a MUCH worse package with different company but we were told they would remain the same. Obviously they didn't.

They removed a lot of key roles from the company and added their responsibilities to other roles without increasing pay.

They got rid of our HR team entirely and replaced them with 1 person who is only on site once a week if we are lucky, but they are always in meetings and never seems to be available. It's also a coin flip if they ever respond to emails.

And a whole bunch of other shady things, but I'll get into what im asking now. A work buddy of mine applied to a position on a different shift. It's an overnight shift which is supposed to come with a 2 dollar overnight premium. It's also a "co-ordinator" role which means its supposed to be 3 dollars over base rate. This means it should be 5 dollars over what the minimum pay is. He got the job but wasn't told what the pay rate was until they brought him the contract to sign. It said the pay rate was $23.65. It didnt mention the overnight premium, but his new boss said that was on top of that. He also said that his loyalty bonuses would not apply to this job and so he was losing them from the pay rate. If he had them he would be making $25.85 before the supposed premium.

The issue i have with this. It's not explicitly said in his contract he will get this premium. So they can choose not to pay him that since he it wasnt in writing. Meaning he'll only be making around 0.20 more than he was which is not what its supposed to be.

On my end, my boss is moving to a new position soon, and has sent their boss an email saying im the perfect person to be their replacement. I know they are salary, not hourly. I know what they make. But every time I've applied for a new position internally, they never tell me the rate of pay for the job until they offer the contract. And if we dont agree there's no negotiation, they just move to their second pick.

Is a company legally required to disclose the rates of pay when it comes to internal jobs before offering the contract? I know if it's posted externally they are, but our company only posts externally for the lowest paying jobs and promotes from within using an internal application system.