In these sort of things, your direct manager probably doesn't even know what you make. There is a tight pay band set by HR and virtually no room for differentiation between employees. There is no mechanism in most roles to truly be rewarded for going the extra mile. The only surefire way to increase your takings is to be active in the employment marketplace and always looking for a better deal.
Working for someone is like this old Seinfeld bit[0], if you want to be rewarded you have to get someone to agree to it before you do the work, once the project is delivered and they are satiated they won't be feeling as generous. "We don't need labor now why are we giving this guy a raise?"
It's not just knowledge. Many of these jobs are TIRING jobs because you are physically on your feet a lot. You just don't have the energy to go looking for another job at the end of the day.
The break COVID gave people was a huge boon to job mobility.
Can you share some details on where you're getting this data? I'd like to dig into it more.
Imperfect information certainly is a thing, but many public jobs have public wage information. Large corporate jobs also have public wage information (say a delivery driver or warehouse worker -- everyone knows what Amazon is paying for these positions). Claiming people stay in these jobs due to ignorance goes against my experience growing up poor, where my parents and their peers constantly hunted for better paying jobs.
I don't know anything about Ireland, but a quick Google for "ireland jobs" leads me to https://ie.indeed.com/jobs-in-Ireland where I can clearly see wages and salaries for many positions.
And that's a segment of people who ought to be very good at using technology to find out that kind of stuff. I would be very surprised if this didn't hold for most other fields. I'd expect the only markets in which this kind of thing isn't common is ones that are extremely comp-focused (finance, say, and maybe sales).
I agree that white collar jobs obfuscate salaries and that power dynamic overwhelmingly favors employers.
That isn't the situation with lower paying jobs, especially ones that aren't salaried, which was what the OP was about. Those low skill jobs (I'd argue baggage handler making minimum wage at the airport to be in that category) openly list wages on the advertisement. Thinking those folks stay in their jobs due to the same information asymmetry is what I'm questioning.
When you were younger, it was worth it to work. Today basic wage often does not even cover rent and other living expenses. You loose money by working.
To get some perspective go to www.daft.ie and try to find studion near airport...
The only thing that was keeping this jobs in place is imperfect knowledge. Most job seekers have a limited knowledge as only know their own past jobs and the ones from close people (and to talk about pay is quite taboo in many countries). And that is how we got here. Even when there is public information, many people have a hard time understanding the implications of the statistics and concrete job differences.
Corporations have thousands of data points and share salary statistics between them.
Staying at home and even firings have helped some people to gain that knowledge.