Why are frontal cyclones mainly active in middle and high latitudes, and more?

Frontal cyclones are mainly active in middle and high latitudes and are more common in temperate regions:

The global atmospheric circulation where cold and warm air flows meet at middle and high latitudes will form a front. The low pressure formed on the ground is affected by land physical properties and other factors, and its pressure center is unevenly and regularly distributed, so the wind directions on both sides of the trough line are inevitably inconsistent, thus forming a frontal cyclone.

The following points should be grasped in the structure diagram of frontal cyclone: (1) Frontal position: Frontal always appears in the trough of low pressure, and the frontal line often coincides with the trough line of low pressure, as shown by lines M and N in the figure. (2) Types and movements of fronts: The two fronts in a frontal cyclone must be the left cold front (M front in the figure) and the right warm front (N(3) in the figure). According to the wind map of the northern hemisphere, it can be determined that the wind direction near the front is north, south and south. (4) Weather characteristics of frontal cyclone: As can be seen from the figure, the front of cyclone is controlled by warm front N, so there is a wide warm front cloud system and continuous precipitation weather near front ③; The back of the cyclone is controlled by the cold front M, so there is a narrow cold front cloud system and precipitation weather near the front ①.