Problem #1 with your argument: you're basing this on a two-person income. Clear demonstration you don't actually anticipate anyone to survive on those wages.
Problem #2: you do not factor in that they will have limited means of promotion without schooling, and seeing how you left $0 in the budget for savings or miscellaneous, they would have to go into debt to go to night classes, etc. Debt, when you are making $8.25 an hour, equals 20-30% interest if they're lucky. This means even if they get the certificates they desire, they will have a negative net worth.
Problem #3: what happens when the Starbucks they work at decides to raise their prices without raising the wages? Then the markets around Starbucks raise their prices. Now our couple cannot even afford to buy groceries on the $100 a week you left them. Which, by the way, is way below their food needs.
Problem #4: You do not factor in insurance: if they have two cars and are two people insurance would cost near $500. so far, with groceries, insurance, and debt, they are nearing -$1000 a month... fun times.
Problem #5: There is this weird fascination with the older generation with not living your life but simply surviving until you're too old and too worn out to enjoy it. If they get a second job, they won't be happy, and they won't be living life... just hamsters on a wheel waiting to retire.
Problem #6: I have a bachelor's degree in management and ten years of management experience. Yet, Companies are not interested in hiring me in any position higher than entry-level, so it is fair to say that assuming they could go to night school to get a higher paying position is an assumption. Every high-paying position I have gotten has been received via networking.. which our couple doesn't have time for while working two jobs and night school; I say night school because no matter how much I network, I still need my necessary credentials.
Problem #7: Oh No! one of their cars sprang a flat tire... that's $100 on a credit card ( remember no money left over for savings) which in 3 months becomes almost $300... for a single tire. Being poor is fun!