Question

Why do various federal, state, and local government programs help raise people’s standard of living?

Answer 1

The government has various reasons for this. first of all, when the living standards are raised, the people will have more disposable income. this allows the people to start buying goods hence the demand will increase. when the demand increases, more tax may also be collected and more supply may be created...this creates jobs as well.
also, an increase in living standards will mean more happy people. this will increase their productivity hence production is increased which can increase amount of tax collected or even increase supply hence make goods cheaper overally. 
last but not least, this will help in improving the health and nutrition of the people as less people will be sleeping hungry and less people will be falling sick. this will allow the government to reduce its spending on the health amenities so that money could be used somewhere else.

Answer 2

because certain groups of people have fewer opportunities to raise their standard of living.