The other commenter already made the point that not all work has an economic value higher than the legally-mandated floor of wages, which I'll take as axiomatically true and won't explore further.
The more interesting follow-on point, however, is that people have to start somewhere, and effects compound over time. Someone fresh out of high school or college is, generally speaking, useless at any given job on day one. Most job training happens on the job, even for people with college degrees. A new employee is a double cost to the employer until they reach proficiency; they have to be paid wages, and they take time away from somebody else who has to train them.
And through that path someone learns not only the job-specific skill, but also the general skill of being a productive member of the workforce: discipline, time management, grit, people skills. Over time this learning compounds, and they move up in income.
The way that a minimum wage that is too high is unfriendly to the already-underserved is precisely because they miss out on that critical experience. Sure, it might seem exploitative at first glance if a local burger joint hires a kid right out of high school and pays them $5 an hour, and doubly so if the kid is from a disadvantaged class. But the fact is that they will learn from this experience (and crucially, more than just about flipping burgers) and level up and move on. The rich kid gets to skip this step and go right into a job that pays $30 an hour, because they have the unpaid internships and the social connections and everything else that makes them more prepared; that is, they have already leveled up to a degree.
Proponents of a higher minimum wage imply a picture where the people getting paid minimum or near-minimum wages are stuck there for life, perhaps for generations. Actual data shows otherwise; only a third of people born to parents in the bottom quintile of incomes remain in that same bottom quintile in their own adulthood. And on the other side, only a third of people born in the top quintile remain there. Under some analyses, the only group that stagnated were the beneficiaries of greatly increased government benefits borne of the Great Society programs in the 60s. Those people were disincentivized from working and therefore never up-skilled.
A higher minimum wage has a similar effect: it will necessarily mean fewer young people join the workforce earlier on in their lives, and again, because their experiences compound, will mean that over their lifetimes they will be worse off.
I have no strong feelings about salary transparency laws, but am generally in favor.