$15/ hr is $2,400 monthly assuming four 40 hr weeks. After tax, you're looking at $1,801 take home. https://smartasset.com/taxes/nebraska-paycheck-calculator#IT0Rc2fc7R
Let's say they pay $500/ a month in rent. Which is about average in the little town of 800 I live in. So now, we have $1301. Let's add in a $200 car payment (on a high mileage vehicle requiring frequent repairs, $50 car insurance payment (liability only), and lets say they fill their gas tank once a week at $35 per pop ($140 monthly). Now we got $911 left.
Utilities in this old small town house with terrible insulation run about 300/ month. Now down to $611.
Individual health insurance premium $456 https://www.ehealthinsurance.com/resources/individual-and-family/how-much-does-individual-health-insurance-cost.
Now we are down to $155. Single line phone bill $60.
Now down to $95 for the month for food, entertainment, medical bills, dental bills, eye care, unexpected vehicle, appliance breakdowns, retirement contributions etc.
No one is making it on a single $15 an hour 40 hr/ week anywhere without a second job, government assistance, or lots of overtime. If you think they are, you're not seeing the whole picture. Don't know how much more I can break it down for you.