If you believe that every system has flaws, then you might be able to see when it may fail. For example, the income tax system has always been ham handed. Those who understood it well enough could always slip between the regulations to avoid some or all of it. In the early days, about 90 years ago, most people ignored them. In the 1940s, they passed payroll withholding and started collecting from those who were employed by others.
When most of the revenues were coming from a large "middle class" the system worked because it was easier to pay the government than to pay a tax attorney to find the cracks. People who were really rich could still afford to pay tax attorneys to minimize or limit their taxes, but it was a relatively small percentage of federal income tax revenues.
But as wealth began to concentrate, an industry of bright financial and legal professionals flourished, allowing more income to be shielded from the IRS. The rich, who got richer, weighed the cost of the tax verses the cost of testing the tax avoidance in tax court and decided the best return was "playing in the gray." The IRS has no choice but to go to tax court when someone challenges them. They do not have enough people to fight every rich person or company. Often, the well-paid lawyers of the taxpayers are better versed on the law than the civil servant IRS lawyers. As the rich get richer, they influence tax laws to gain a greater advantage. Eventually you have a society of people who are either too poor to pay much tax or a few too rich to need to pay tax. That is when the tax system fails. Frankly, no tax system can succeed when the money is too closely held by a few.
The irony is that we tax productivity. Imagine a company going to its most productive people and cutting their pay as they worked harder and better. There is a better way to collect federal revenue --
http://www.forbes.com/sites/kellyphillipserb/2011/09/02/guest-post-income-tax-alternative/ .