Labour worth is not decided by law, but by cost-benefit. If you make people unable to work for less than the minimum wage you're excluding a huge chunk of people from jobs. Artficial attempts to raise wages will make the employee cost higher than their benefit, forcing the employer to reorganize.
A minimum wage law might be made, but that has no influence on labour value, you're simply saying people have to work for a minimum amount or don't work at all. This black and white view on economics is what causes income inequality. Limiting industries hurts everyone, not just the top.
You still haven't answered how they're excluded from the job market. A minimum wage raises labour value as long as employers don't get greedy and dramatically increase inflation. Not limiting industries hurts everyone, not just the poor.
With these labour limits you are saying ''You have to work for *set amount* or you don't get to work at all!'', which is often followed by pretending to catch them with welfare programs while being the very reason they got there.
This creates inequality and unnatural differences between incomes.
Greed is the causal factor in the argument. It is not an ad hominem attack to avoid the argument in question. Greed causes companies not to want lower profits. This causes price raises. This hurts the poor. Take out greed and the top still profits while workers earn more.