Professionals with credentials have some power in the market, they can command a price.
Unskilled labour cannot. Without regulations, they would be paid $2 an hour, i.e. what the market will bear.
If you thought the 'Dollar Store' was cheap, imagine the '25 cent store' - where people survive on extreme minimums.
Favellas and tiny illegal homes pop up, without plumbing etc. and entire mini-industries are created around the ultra-low working class.
A $1 Trillion dollar corporation has 'all the power' an individual has none, and it's existential: 'work for just enough wages to barely keep you alive or die'. That's what the market will push towards and a lot of people will think that it's fair.
The market allocates money based on power. That's it. In a purely market based anything, if you don't have power - you die, or close to it.
People living in favelas with no plumbing can't hope to send their children to school etc. so it creates generational problems.
This is why we have minimum wage, safety laws, anti-discrimination etc.
That said - unions can often be a detriment and their power can be good only for the members and nobody else. It's not a black and white issue.