To understand how this happened in America, consider this partial history of this once-proud republic. Through stubborn persistence, powerful understanding and love for liberty, our country was born, following a course symbolized by the unalienable pen of Thomas Jefferson. Our founding fathers screamed that British attempts at direct taxation through laws such as the 1765 Stamp Act were intolerable, and finally rebelled, revolted, and won a questionable peace. Thereafter, an aborted attempt at a union of the states culminated in our current agreement of 1789 that solidified these united states. Our country was founded in common law according to Thomas Jefferson, but as early as 1799 he noted in a letter to Edmond Randolph that the law had already slipped into equity or chancery, which he believed to be scourge of freedom.
Equity courts come from the ecclesiastical side of justice.
The king ruled the courts of law, and the church controlled equity. Equity has many noble honors such as being the theater for inquisitions and star chambers. Common law grew from the desire of the common man to have a forum that would net swift, inexpensive and final results for the common folks. Common law can be harsh, because the rule of law is inflexible. Just as you do not plant corn in November because of Nature's Law, you do not violate common law and expect a harvest.