Things were famously so much better before NMW, when we had casual contracts, and pretty much the employer-driven free-for-all you are advocating.
Except, no they weren't. We still had rampant unemployment, wage slavery, and enormous proportions of our workforce living in poverty.
Guess what? Commercial business is driven by one thing only, profit.
There are lots of roles that just don't exist because the economic value is less than the minimum wage
Yes, because employers can't pay minimum wage and still turn a profit from these "roles", so why is your expectation that someone should fill them and live in penury regardless?
Anyone with an ounce of common sense is not going to go and work for a mercenary employer who cares not a jot about them, for a pittance wage that sees them living in poverty anyway, when that job comes with no prospect of advancement and carries no benefit or perks, and especially not against the backdrop of gutted employment law which also means no leave entitlement, legal protection against vindictive employers, no SSP, no pension, etc etc
You would genuinely be better off sat on the sofa, because you wouldn't have the expense of work, and you wouldn't have the headache of trying to find childcare, or be at risk of missing out on xmas etc because your employer invariably expects you to work holidays and so on.
We've been in your situation before, and it was utterly fucking miserable.