Forms of unusual favor are not limited to travel. The provision of food, drink and clothing when needed is also discussed; Maryam's provision is the primary Qur'anic illustration.
An immediately unknown cause does not by itself establish a break from custom. Once an event is reliably established, its nature and relationship to divine power can be examined.
Not every fortunate coincidence, gift or apparent answer to prayer must be labeled a technical karāmah.