What if you bought a pair of shoes exactly like the person ahead of you in line, but you had to pay an extra $10 in sales tax because of your income? What if the next time you bought groceries you had to pay sales tax on that pound of hamburger but the person after you didn't, because you earn more? And what if when you die, because you were frugal and saved a lot of money during your lifetime, your estate was taxed higher than more irresponsible people that wasted their incomes and had nothing left?

Does any of that sound like paying your "fair share"?

That term gets a lot of press these days. It's always been around, but in 2011 billionaire Warren Buffett proposed the so-called "Buffett Rule": anyone earning more than $1 million should pay at least 30 percent of it in taxes.

Since then, "fair share" has become more popular in liberal circles. The idea sprang from Buffett's observation that his secretary paid a higher income tax rate than him. Note the subtlety there – a higher tax rate, not higher taxes.

I'm certain he paid a lot more in dollars to the Internal Revenue Service than his secretary. But should he have to pay a higher tax rate? His fair share?

What is a person's fair share? The top 1 percent of income-earners in the United States pay 44 percent of all individual income tax revenue. The top 20 percent of earners pay a whopping 84 percent of all taxes. This is while 45 percent of adult taxpayers pay nothing at all.

There's no question some people are less fortunate than others, and some people truly need financial help – but almost half the population? Does anyone believe the 1 percent use anywhere near half of all the services provided by the government? Do they get their fair share of government programs?

It's a ludicrous argument because Buffett and Bill Gates don't need welfare. They should probably pay more in tax dollars than someone living on minimum wage.

But how much more should they pay? Millions? Billions? They should pay their "fair share." Proponents like to ignore the dollars paid and point instead to the tax rate paid as a percentage of income, so let's look at it that way.

According to the Tax Policy Center, the top 1 percent of earners pay an average income tax rate of 23 percent. This is clearly below the Buffett Rule, since this group averages an annual income of $2.1 million dollars per year. But that 23 percent is seven times the average tax rate paid by the other 99 percent of the population. While we can always search to find a specific millionaire and compare them to a specific minimum wage worker to show that the worker pays a higher tax rate, in aggregate it simply isn't true.

Liberals also have the perception that people with high incomes don't work hard. For example, Hillary Clinton has said, "It's outrageous that multimillionaires and billionaires are allowed to play by a different set of rules than hardworking families, especially when it comes to paying their fair share of taxes" [emphasis added].

It may be true that lower income occupations have a disproportionate share of physical work, but that doesn't necessarily mean they're harder. A person collecting trash or digging a trench may sweat more, but after eight hours they can shower and relax. An international bond trader, Fortune 500 CEO or even a moderately successful small business owner works a lot longer than nine to five.

Should hard work be exclusively measured by how many calories are burned? If that's the case, a lot of professional athletes - earning millions - are hard workers and deserve lower taxes. They should pay their fair share based on physical effort, right?

If Buffett or Clinton think their tax rates are too low, why don't they pay more? Asked this question about President Obama when Obama said he should be paying more in taxes, his press secretary dismissed the question as a "gimmick."

Really? A gimmick that was established by the Department of the Treasury and has been around for more than 170 years? Since 1843, the department has maintained a special account called "Gifts to the United States" where individuals can voluntarily pay more than they legally owe in taxes. Last year, the total collected was a little less than $4 million dollars nationwide.

Maybe that was Buffett's fair share?

Kevin Cochrane teaches economics and business at Colorado Mesa University, and is also a permanent visiting professor of economics at The University of International Relations in Beijing. Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.