It always amazes me that this has never been rectified within the corporate culture. Maybe the percentage of employees that look is so low that the risk of losing them isn't worth the cost of proactively keeping them happy with their salary?
Where I presently work, about half of the staff have migrated from a technical/support (but not IT) side of the business to the "productive side of the business.
They all get the national minimum wage plus a few coins, to make them happy. Where they came from, where I am, is minimum wage part-time/casual (legally part-time/permanent, contractually casual). If anything goes wrong - and with our failing electronic equipment it happens all the time - then there are warnings, there is much screaming and swearing at, and so forth.
Since we recently merged with another business, the new hires - who are fresh out of training with no experience and rather poor skills in our particular area - get about 35% more pay, better conditions, and the managers are far more tolerant of their mistakes. (You produced under 40% of your weekly minimum requirement? That's OK! You've opened us up to serious lawsuits because of your poor work? No problem! You smashed the state-of-the-art equipment we bought you, and then snatched your supervisor's unit to replace yours, and she couldn't do her job? That's fine!)
The lowest paid of these staff, the internal promotions, are responsible for all our production and training at a fraction of the pay. The new hires are classed as full-time/permanent, the internal promotions are part-time/casual and so can be dismissed at any time with minimal notice. Needless to say, they're leaving as soon as they can find a job anywhere else.
If there's at least 2 business doing this, why don't you just go to the other side and vice versa? There should be new openings everywhere everytime, and you could demonstrate that you're worth the 35% pay increase.