If you don't have any narrowness requirements, you can have a job where the range is $50k-500k, which is useless. If you narrow it to — let's say — 10% of the midpoint, you can say $180k-220k, but then you're not allowed to hire the perfect candidate who won't accept less than $250k, even though you would actually want to pay this much given that person's skills. If the candidate is allowed to negotiate upwards, ranges may gradually, over the course of years, drift downwards, with an implicit understanding that they are unrepresentative of the actual salary you are likely to earn.

With an infinite number of employers and an infinite number of candidates, you would always be able to find the perfect candidate for your mix of requirements and pay them the exact salary that matches those requirements. The real world isn't like that, though, and if you, as an employer, have an offer available, you will get candidates who are under and over qualified for the specific offer you had in mind, and you might nevertheless be able to find a spot for them at some salary that both of you are willing to accept.

1. To be meaningful at all, the legislation must only allow narrow ranges, e.g. 10%, so that employers can't put 30-90K in the description.

2. In addition, you would have to make the application very specific to a given position. If the employer can say "you don't qualify for L7 that you applied for, buuut... we could transfer your application to the L5 track", then we are back to where we started.

3. On the other hand, any super-rigid rule like this will hurt both employers and employees who are actually trying to fill a real position. It will hurt even more the few remaining companies that are looking for people and not just labeled cogs in the machine.

I want this to work, but it has the smell of compliance theater.

The problem is, if you haven't noticed yet, that it might work for a low/semi-skilled job like e.g an estate agent "£25-30K + £10K OTE bonus depending on experience". But it doesn't work for artistic or highly bespoke jobs like doctors, lawyers, some types of engineers etc. where the salary range can be much larger. Does it really help anyone to say, "Wanted: Software Engineers. Salary £25-100K depending on experience and skill"? Lots of ads already show that, people might think they are worth near the top end and get low-balled with an offer (fairly or unfairly) whereas the people who are not confident are still likely to get paid less money.

As for telling everyone what everyone is paid, that opens even more cans of worms. It is not always easy to describe that the other person gets paid £10K more than you because they have e.g. "a better attitude" (says who?), "is more productive" (based on what?) etc. and tbh, it is not usually completely objective.

Sometimes ignorance is bliss. If you are all about money, then ask for what you think you are worth and if you don't get it, move jobs. I think what other people get paid should be nothing to do with you.

That entire sentence could be stricken out and nothing would change.