I can think of several examples. Here's one.

Businesses want to be able to higher high performers or those who the firm knows have other options and can demand a higher wage, which means they must pay them more than they would like to pay the average worker, so the ideal situation is to have multiple ranges, for example one for the average worker and one for the workers they really want to hire. So under this law they'd publish a big range, like this position pays between $X and $2X, but if the firm publishes that range, it makes the average worker think they can get 1.5X -- after all that's the average -- and then they become resentful when they are offered only X. In fact most workers would be upset that they are getting X.

Of course you could try to make a different job title -- e.g. Y and good-Y, and then say that Y pays X and good-Y pays 2X. But then you have to explain which job you are applying for and why you are not being promoted to good Y. It's a mess. Particularly in our current zeitgeist when there is an enormous amount of envy and obsession with equality, disclosing real salary ranges is guaranteed to generate lots of resentment and is the last thing the firm wants to do. And God forbid if the high performers are not perfectly distributed along whatever identity category is viewed as most critical, as then you could be open to lawsuits, etc. So think of this as the flipside of the UC System refusing to take SAT into consideration. UC doesn't want any objective measures as inputs for the same reason that firms don't want to disclose objective outputs. It's really the flipside of the same coin -- not wanting to offend those who insist there are no differences between groups by either refusing to collect the data or refusing to disclose the data, which if taken into consideration or disclosed would reveal that there are in fact differences between groups.

Now in some cases the firm is in an industry where there is not much difference in employee productivity just due to the nature of the job. If you are serving coffee, then a slow coffee server is not much different than a fast coffee server. Same thing for a property manager. Hospital nurses are generally not paid based on performance, it's so regulated. So in those cases you don't care, you can disclose. But in other cases it's not. So some firms will avoid CO and others wont. I suspect in most industries you do not see really big differences, and so most employers will be fine as they are in the hospital nurse/property manager bucket. But some wont be. E.g. in tech, there are big differences in productivity. Also in sales occupations, there are huge differences in productivity. It really depends on the occupation/industry. Similarly for education, while it may threaten the worldview of UC admins to look at SAT scores, it would not threaten the worldview of a community college to look at GED scores, and so community colleges can still take GED scores into account while preserving the we-are-all-the-same view just as the property management offices, health care admin, and coffee shops firms can disclose salary-ranges and not be vulnerable to charges of discrimination.

Of course these are all hypotheticals. If you want data, then look at which industries are the ones more likely to give CO a pass and then take a look at their compensation structures or what type of labor they are hiring to see which firms believe they will be faced with larger costs than other firms.

Then there is the issue of special-casing your HR processes for Colorado, which some firms may not find as being worth the hassle.