I have had this kind of conversation with HR and management people that I report to, and there are two major issues.
1. You rarely, if ever, screw up your current assignments. That means in their eyes that your job must be easy. Therefore, they could replace you if they need to, because the work is easy. The corrolary is that, if you do make a few mistakes, then you are incompetent and they could replace you with someone earning less money if they feel the desire to change a known (and apparently sub-standard) performer for an unknown, with the attendant training and ramp-up time. Both of those translate in PHB-speak into "you are overpaid, and lucky to have a job".
2. Management and HR need to be educated about the complexity of your role and the value that you add. However the kicker here is that they do not want to be educated - education is for people who are ignorant and need a perception-adjustment. Management and HR feel they know everything they need to know, and more, and they know more and better than you. Can HR do your job? Of course not, but they feel they can identify and hire someone who will do your job - that process gives them something to do, a reason to justify their existence, and they will take that opportunity if offered.
Trying to educate HR/Management will probably come across as agitating and rocking the boat, which will often see them shuffling you toward the door - in their eyes you may be good at the job or you may not, but the workplace is about the team, and you are showing a lack of team spirit so we should get rid of you and find a "team player"... In this case, the "show us some evidence of another pay scale we should be using" request is an invitation to show them that they are not doing their job right. If you fail, they were right and you were wrong. If you succeed, you were right and they have bruised egos. Do you really want to bruise the ego of the people you report to and who handle the HR at your employer?
The best way to educate HR/Management is to take the role, then once you have a few months'/a year's experience, or the successful delivery of a couple of major projects and you find a similar situation which offers a higher salary, take that discretely to Management and point out that competitor X has offered you x% more money for the same work.
It also puts you in a potentially stronger position, with a stronger job market in 6-12 months time. Or, if you suspect that the job market is going to stagnate or contract over the next year, then being an established actor at a company is usually a better prospect than being the new guy trying to get up to speed and learning both a new company and new aspects of your role.