I think the cliche is true for most people, as discussed in a recent essay. Students who do well in algebra will earn more than those who don't primarily because they are more intelligent on average, not because many of them will be using algebra in their jobs.
And if you read on, it concludes by basically saying the reason the people are more intelligent is because they learned algebra.
When I say that I use algebra all the time, I'm not referring to the quadratic equation or any particular algebraic function. I'm referring to the concept of constructing an expression based the relationships between known and unknown values to solve a particular problem. Once you've got that expression, it's usually just a matter of simple arithmetic to solve whatever problem you're trying to solve... so it's all in the expression. And the logical processes behind constructing and manipulating expressions is learned in algebra.
Also, I'd say that while the execution of higher math isn't necessary to the performance of most jobs, the understanding of higher math is essential to accessing certain concepts. Electronics engineers and technicians talk casually of sine waves, but if you don't know trig, that statement is meaningless.
When I was in school in the Navy, we spent a whole week on vector mathematics, manually calculating a firing solution to intercept an aerial target with a ballistic weapon fired from a pitching and rolling deck. We never used vector mathematics again, because that's what the computers are for. But we did acquire a deep understanding of the complexities involved in a firing solution, from which we appreciated the importance of getting a battery alignment check done properly, or the impact to the system of losing windbird or gyro data.
Here in this forum on giftedness, an important mathematical concept that helps us understand our kids is the standard deviation. You don't have to calculate it, but you do have to understand it.
