How does creationism explain vestigial organs?

Note: for simplicity, this article uses the terms created or creationism in reference to special, immediate creation of organisms in their current forms, as opposed to those that developed over time from prior forms. Some forms of “creationism” involve both divine intervention and micro-evolution, but, for the sake of brevity, the terms are used as described.
If animals were created and did not evolve, why do they have vestigial organs? That is, why would God create an animal with parts it doesn’t need? Some organs are referred to as “vestigial” because they are assumed to be a “vestige”—a leftover—from an earlier evolutionary form. The term vestigial implies a lack of use, purpose, or function. Common examples in human beings of “vestigial” organs are the appendix, the tailbone, and nipples on males. Critics of creationism suggest that these are useless, inefficient, or stunted body parts and are more likely the result of prior biology than special creation.
The first question to consider is whether or not the organs in question are actually vestigial. If an organ serves a function, then it’s not vestigial. Actually studying a so-called vestigial organ frequently shows that it’s not so useless after all.
For years, the human appendix was held up as the classic example of a vestigial organ, or at least a poor design. The appendix is sometimes removed as a result of inflammation or tumors, without any noticeable side effects. This, supposedly, is evidence that the appendix is a superfluous organ. However, more recent studies have suggested that the role of the appendix is to store beneficial bacteria used to re-populate the digestive system after illness. Surgical removal is still needed in case of infection, but the organ is not, in fact, without a purpose in the design of the body.
Similarly, pop culture has often considered the tailbone to be vestigial and useless. This criticism rarely comes from actual scientists, however, since the tailbone serves as the point of connection for various tendons and muscles. It also stabilizes the body when a person is in an upright seated position. Its scientific name is the coccyx, but, as its common name implies, the “tailbone” is assumed to be a remnant of an ancestor’s tail. But the coccyx is far from useless, and we would have a hard time without it.
If the “vestigial” organ seems to serve no actual benefit, the next question is whether or not there is some compelling reason to include it as part of the body’s structure. Critics of creationism have sometimes pointed to the presence of nipples on males as something nonsensical under special creation. Males do not provide milk, so why would they have vulnerable organs that serve no useful purpose? The most reasonable answer to this is, truly, greater efficiency.
When purchasing a car, there are often several different models available. At greater cost, better features can be added. Those features sometimes add switches, buttons, or dials to the inside dashboard. However, it would be very expensive and wasteful for the car factories to create a unique dashboard for each set of options. This would require a completely different set of tools, machines, and parts for each version, not to mention additional records and quality controls. Instead, the most efficient use of the machinery is to make a single dashboard for every car, and those without the fancier options will simply have the unneeded holes capped with covers.
In a biological sense, this is why males would still have nipples, assuming creationism. The “machinery” that creates the organism’s body, DNA, doesn’t need the added complication of completely different chest designs for males and females. It’s more efficient, less complicated, and less prone to genetic errors to simply have a single “model” for both sexes, though only one has an actual function for those organs. What seems like a waste is, actually, biologically more efficient than custom organs for the two sexes.
Many of the organs we now know to be useful were assumed to be useless by prior generations. And some features make sense from the standpoint of a streamlined genetic code. By and large, those two considerations explain the existence of vestigial organs, from the perspective of special creation. Knowing the wisdom of God, we know there is some purpose to those features, whether we fully understand it or not (see Psalm 139:14).