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.