Criticism about some types of exercises

There is a certain type of exercise that I don't think serves a purpose in teaching functions. In Stewart's textbook for example there is an applied project about using the derivatives to design a roller coaster. This type of exercise attempts to teach functions and calculus by applying it in a real life problem. However, there is a gap in its conceptualization. The applied project in the book tells you that you are designing a roller coaster and to do so you employ a quadratic function. First, why does the roller coaster have to have the shape of a function? The graph of a function is one thing. The shape of a roller coaster is something else. In the same way we can think on a parabola's segment as being a piece of the roller coaster, we could think on other functions such as the exponential or a sine. How do we decide which function to apply then? The book does not tell the answer, expecting us to make make the relationship between the graph of a function and the roller coaster with some kind of magical reasoning.

Suppose that there is a problem about building a bridge and some types of bridge have arches. The problem suggests applying the graph of a parabola as the shape of the arch because it's cool or pretty. Who writes those textbooks and proposes such problems? Mathematics, physics and engineering aren't about building structures out of beauty or faith. Of course there is architecture, art, comfort and even politics and religion in building structures. But a textbook shouldn't give the wrong idea that calculus and graph of functions can be simplified like that. To build a bridge, a roller coaster or other types of structures is a much more complex task than graphs of functions alone.

While I was reading an admission exam for some public university I came across a certain physics problem. It described the problem of a falling brick from the top of a building. The person who dropped the brick yelled to warn another person below. The problem was to calculate the time it'd take for the brick to fall and the person below to hear the warning and escape a possible death or serious injury. We sure know that the speed of sound is greater than the speed of a falling brick. However, I think that such problems oversimplify physics and mathematics in a way that could be deceptive. A similar issue was presented in the movie "The Miracle of the Hudson Flight". In the movie the captain was criticized for landing on the river because, according to some calculations, he should had had enough time to return to the airport and safely land there. In response the captain argued that there were multiple human behavioural and psychological factors that made such decision, returning to the airport, impossible to take.