>since economics is a rather new science
Isaac Newton's Principia was first published in English in 1728. Adam Smith published The Wealth of Nations in 1776. That's a 48 year head start out of the nearly 250 years we have had both physics and economics.
Economics as a serious empirical science is a post-World War 2 phenomenon. Ptolemy had better data about the planets in the second century than we had about the economy in the early twentieth century.
Besides, there are actually a lot of things that economists agree on: https://gregmankiw.blogspot.com/2009/02/news-flash-economist...