“Why are there airbags in cars” is answered wit “to protect the occupants”. it would be inane to give a a causal answer, such as “because someone fitted airbags”.
“to protect the occupants” is merely syntactically simpler than “because of the builder’s desire to protect the occupants.”—the two statements equally well indicate causality.
“to protect the occupants” is merely syntactically simpler than “because of the builder’s desire to protect the occupants.”—the two statements equally well indicate causality.