its a bit complicated - he may be making more then they at the age bracket 20-30 but he will be making this much till the end of his carrier while they may be making 1500-2000 uero in 25-30 then take managers position and make 3-4k + while siting comfortably in office instead working hard manualy and then at 50 + when he will be still making 3k a month they will be in directors postition making 10k+ while still sitting comfortably in office while he still will be working very hard manualy everyday .
its all about whether you are ok with hard labour till pension and earning more or less the same your whole life or gradualy makin more and more while having comfy office job.
your nephew will start seeing difference around age of 40 when his body will start to "corrode" much faster then their while he will have no other choice but still work very hard.
practical skills will be for sure much more beneficial then some random shitty degree in liberal arts - but if you have good degree from good uni you will easily overtake earnings of blue collar by the age of 30 - you just need to sacrifice few first years while learning your job .