It's actually not hard at all, it's only a problem for companies if they fail to keep it secret. Norway has had their tax records public for ages https://www.weforum.org/stories/economic-growth/norway-can-s... and their society and economy seems fine, except they it's extremely easy for new grade to know what they can ask for.

The "complications" are basically employer and manager propaganda because the information asymmetry suits them better than people realising they are undervalued and leaving

Ranges are still somewhat useful. If they low-ball the upper bound, anyone expecting close or above the upper bound is unlikely to apply. So there is incentive to be honest about that end at least. But as an applicant (or current employee), knowing the upper bound the company is willing to pay for this position is useful information for salary negotiations (and to enable you to spend your limited time and resources in applying to well-paid jobs)

Obviously it's not perfect. But as you say, it's a difficult problem. And salary ranges are at least something

In my experience, they will offer a bit above the advertised minimum of the range. So if I wasn't happy with £60,000, I wouldn't consider that job, and I definitely wouldn't apply on the basis that maybe they'll offer £90,000.

I think that it does. If you’re looking for a 120k a year job you know that you won’t have to apply.

Of course it helps. Often if a company is not advertising their salary it's because they're either trying to lowball you or the current staff

That's fine though - As long as they're publishing the actual range that they like realistically pay someone, there's literally nothing wrong with that.