Many of the very poor do not have jobs, and no minimum can help them at all. Others are paid more than the minimum, but are still poor. However, it would be a mistake to argue that the minimum achieves nothing in helping the poor. Some 1.9 m workers will be be affected by it - that is one in 12. On average, assuming they are elevated to the minimum, they will be paid about a third more than at present.
Young workers tend to get paid less than older workers.
That sometimes reflects the fact they are given training by employers - and hence get paid for their time in the form of extra skills as well as in cash. Sometimes it reflects the fact they are inexperienced and untried, and hence are worth less than older staff. Sometimes it may be that employers can get away with paying them less, because they tend not to have mortgages and families to keep up. Whatever the reason, if employers want or need to pay less to young workers, a miniimum wage law that forces them on to the same rates of pay as older colleagues could potentially damage their employment prospects more than that of their older colleagues. So, it can make sense for young workers to have their own, lower minimum.