In its most basic form (which I'll discuss here for simplification's sake), it is a guarantee of a minimum income above the poverty line for every citizen.
The country requires a minimum wage because workers paid below the poverty line have an added cost on society.
Depending on the state you reside in, the laws may make it difficult to file if your income is well above the poverty line.
For instance, a divorced women with custody of her children is more likely to live below the poverty line.
Children living in low-income households are less likely to be enrolled in ECE than those children in families living above the poverty line.