Lenses are fitted based on the diagonal measure of the image sensor (or film format). This measure is the diameter of the required “circle of good definition”. Camera lenses project a circular image even though this image circle will be cropped by an image mask to craft a rectangular format.
As a rule-of-thumb the focal length fitted will be about equal to this measurement. Such a lash-up delivers a “normal” perspective. A lens with a focal length longer than the diagonal measure is in the realm of telephoto. A lens 70% of this value or shorter is classified as wide-angle”. Most cellphone cameras are fitted with a moderate wide-angle.
A wide-angle lens, with its shorter focal length, tends to deliver a circle of good definition that is too small. It takes special care to construct a wide-angle with an adequate circle of good definition. Naturally this runs up the cost.
A long focal length lens is far easier to make than a short focal length lens. A short focal length lens must have a steeper curve (figure). This translates to a lens that is fatter in the middle. It is this feature that gives the lens the power to refract and focus in such a short distance. All lenses suffer from aberrations. These are misdirected light rays that degrade the image. To mediate, the lens must be a sandwich of lenses, some with negative power (concave), and some with positive power (convex). Making a small multi element lens is no easy task.
If the lens is made 3.3mm in diameter, to achieve an f/1 lens the focal length must be also 3.3. That’s difficult! If it’s a 3.3mm diameter operating at f/1.2, it must have a focal length of 2.96mm. We are talking the laws of optics. In short a longer lens is better and they cost less to make.