Salaries are political
Pay is a result of a political process in any outfit.
To be fair it is hard to know exactly the "going rate" for a skill set in a given location and so it can be rational to start low and work up.
The problem is that to get more money, the boss of the group has to go to his boss or HR or the client and ask for more and sometimes he can't get it.
So a persistent low ball offer tends to mean that your immediate boss is politically weak, which in my experience is a good predictor of your job being crap.
I have had one skill which meant that for one very specialist role I was pretty much the only person in the country who could do it and had proven in the interview that the people doing it already were flatly lying.
Short version: They were using s/w I'd helped develop and the suppliers claim that "it had been in service" since before we'd ever released any version of it
This was the Docklands Light Railway, a non-trivial project and the agent who put me forward was quite smug that he'd found me and he had earned that smugness.
The DLR offered rather less than half the going rate and an expenses deal (I would have to travel often to Canada) which would have left me on shelf filler money.
I declined and the DLR kept saying "we pay X" where X was this silly little number and it was in a good market, so I was far from desperate.
I heard later they'd hired some guy who bullshitted that he'd had the skill and as you may recall the DLR has had quite a few s/w problems.
The core problem was that never spoke to anyone that actually cared.
The management level that interviewed me had financial limits and as long as they paid people according to policy they had an easy life. Their management were "Management", they neither knew nor cared how stuff worked or even if it did as they spent money at the right rate.
Even the agent didn't care, his cut was pathetic and he knew as a recruiter that if you place someone far below market rate some combination of these N things will happen
1) They will quit suddenly once they realise they are underpriced
2) Their resentment will cause them to do a bad job, somertimes a *very* bad job
3) They are fairly priced, they are only worth what you are paying and are likely to be incompetent
4) They have some non-trivial personalty defect