There are only enough full time jobs for around 50% of Americans...
There is something called an unemployment rate... it means that there are fewer jobs than there are job seekers... so there is a substantial percentage of people out there without work, living in poverty, who do not shoulder the blame...
Sure, plumbers can make reasonable money. But can we have a nation of specialists? No. They only represent a small percentage of job openings in the country. The fundamental tendency of capitalism is to reduce more and more jobs to unskilled labor, as it increases competition among workers, driving down wages and pushing up profits.
Yeah, you might be able to live comfortably on 25-45k. But try doing that in an expensive area, with a stay at home mom raising two kids, while saving money for their college tuition, setting money aside for retirement, taking the occasional family vacation, maintaining one or two cars and paying for all the gas (can easily hit 1000/mo for two cars), paying a mortgage, property taxes, etc...
A family with two cars (driving them >3000 miles a month seems a bit over the top but if so say so), that owns a home, takes vacations, is setting aside money for retirement while also saving for college tuition is doing pretty well imo - and yes, that's easily obtainable making $40k/year - hell they can even have cable TV, cell phones, and eat out of the house every now and then. This is the typical American... You can even sit at home smoking pot for 3 months of the year earning 30k and still afford this - ask Neo.
Now you're saying all jobs are specialty jobs? Really? Lets list jobs than can earn more than 40k/year: General assistant, janitor, plumber, fire fighter, police officer, welder, sales person, business owner, waiter (yes I know several waiters that make more than 40k/year), bar tender, pot grower, manager (of pretty much anything), receptionist, construction worker, taxi driver, deliver man, painter, garbage man, postal man, most any government job, teacher, publicist, nanny, house cleaner, dog walker, day care attendant, ...
If you're working entry level at walmart, target, Mcdonalds, taco bell... then you're right, you won't be making a ton of money. I wouldn't recommend these lower lower tier entry level positions if you want to support a house and a family. To say the majority of jobs out there are minimum wage jobs is a bit silly.