Very dangerous to use wikipedia as a font of all knowledge. It can lead a person to believe it explains everything. IT DOES NOT!

I am not going to argue the causes and cure of the famine here. You will all believe what you want to believe. My take is that the crisis was woefully mismanaged but the fatalities were not a result of DELIBERATE government policy.
I have found nothing to support the idea that Irish labour was imported to drive down miners wages. What time period are we discussing? Elizabethan, Victorian, WW1,WW2, postwar. I suspect another figment of your imagination.