A few people have read into this episode far to much. One broke it down to what they SHOULD have done. I don't get that. It's a fictional TV program that told a charming yet telling story.
The tax rate for the top earners at that time was in the 90% range, down to the 70% range until the Reagan era.
Simply put, there truly are consequences for just about every decision we make but not necessarily horrible ones as in this episode.
This couple is neither savvy nor worldly; just an average, everyday hard working couple who stumble upon something otherworldly and are certainly not prepared for what is to come. They wish for what alot of people would; money and power. It's like all the people who win the lottery and are broke and bankrupt a couple of years later.
Even if they had wished for the taxes to be considered, they would have had other issues; people coming out of the woodwork wanting money, threats, burglary/robbery, sense of entitlement or snobbery overtaking their sensibilities, poor spending decisions......
These days we see so much greed, avarice and deception. The Internet, social media, charitable sites, credit cards, lending practices, the stock market, casinos/lottery for example - the idea is to make life more convenient, entertaining, helpful and interactive - well they have all been rife with staggering consequences that have actually ruined people's lives.
The moral is to be happy and appreciative for what you have, work hard for what you want and if it is too good to be true...yep, it is.