The costs for items have absolutely not basis in reality, and everything to do with psychology. There are decades worth of detailed sales data on every conceivable product at every conceivable price point and companies charge the most profitable price, with sales to purge inventory. One need not look any farther than JC Penny's to see the result of consumer friendly practices. It's simply the most purified form of 'what the market will bear' but it does stand to point out that the actual 'cost' of that cheeseburger is roughly 10 cents, building, power and employee included, and they charge 4 bucks for it.
You extremely right that minimum wage was never supposed to be a monthly salary. However this was also put in place when there were ABUNDANT blue collar jobs and even in the lower end minimum wage areas one could spend years there and obtain a management position. You could have a supermarket manager who started as a stock boy, went to check out clerk (a low-decent paying job back then) to manager over 20 years. Same for any company really, that's where retirement ceremonies and the idea of 'the gold watch' came from. However if you look at hiring practices now? Simply to many of them are hiring people for 2 years as temporary workers then letting them go. Or hiring with VASTLY over-inflated requirements so they can hire people on a work Visa.
The wife going to work certainly affected the economy, but wasn't devastating. At least until 2 working parent households became the norm, and later the expected. Given that men and women enter very different work pools and women working were never really THAT unknown in things like child rearing, education, health care, office work, garment production, and food prep/service. Though at this point where it's expected for both a wife and husband to both be working simply to pay rent as their kid grows up entirely off of TV and that state funded daycare they call education it is certainly a massive problem.
The real problem with the economy is that government is a tool of corporations rather than its regulator and rival. Now before any libertarians jump down my throat let me explain, because text doesn't convey tone very well please take this as simply my interpretation of the economic problems. Very large business interests have, via supreme court decision, given themselves the authority to bribe government officials to their hearts content. They use this power exclusively to pass business friendly laws that are friendly only to their exact type of business. Tax code loopholes are put there almost directly by large corporations that have already set their business up to take advantage of the loophole. Meanwhile they also have representatives pass regulation that is unnecessarily harsh on businesses past a certain break point. A lot of 'overregulation' is put there on purpose to stop new businesses from ever getting off the ground and for small businesses from ever having a chance to grow. With of course the added bonus of providing an easy scapegoat that can be pointed to in the news so while people fight over it they can continue to reap the benifits of a slanted status quo.
This is very much the only reason you don't actually see a congressman come up with this supposed 'fair tax code' that they like to say could exist. Think about how many years this has been an issue and how not a single representative has presented a plan to revamp the tax code that isn't just playing to their base with some idiotic version of the flat tax that mathematically wont work, ever. Simplified tax codes are certainly possible, but as the people taking most direct advantage of them are the same people who fund the campaigns there are precious few who can even speak out about it in earnest.
But, that's really just the problem. And like any problem there are plenty of solutions. There are libertarian and socialist ways to fix things, some are better or worse and some fix different things but they can fix the problem. I have always likened it to planning a trip where someone wants to fly (the fastest) and another wants to take a train (the safest). Only for petty feuds to result in a group of people angry that their is a steam engine on the tarmac with both sides blaming the other.