Is it necessary to install a laser sight for light weapons?

I often see laser sights hunt installed on pistols and rifles in movies. Is laser sight really necessary for combat troops?
Popular art comes from reality, but it is often divorced from reality for the sake of art. In literary works, for the convenience of visual performance, laser sights that emit visible wavelengths appear mostly, and there are many different solutions to this type of laser sight.
According to the power of the emitted laser, the lighting conditions of the surrounding environment and the dust density in the air, sometimes the laser will reflect a track in the air, and sometimes only leave a light spot on the illuminated object. The former phenomenon (trajectory) is rarely seen in daytime and bright environments, while the latter (light spot) is also easily confused with other reflected light or background patterns. Therefore, the use of visible laser aiming is only meaningful in dim and low light conditions.
Moreover, its visibility drops extremely fast with distance, and it can be used for more than ten meters at most. It can't reach the distance that needs to worry about the difference between it and the ballistic curvature. But like other sighting equipment, the installation of the Red Laser Sights & Green Laser Sights must be spaced apart from the bore axis, sometimes as high as two or three inches. This will require a holdover between the aiming point and the actual impact point. This is especially serious in very close range shooting. The problem cannot be solved by returning to zero. It can be realized with a very simple linear geometric principle. The laser aiming point is helpful for maintaining muzzle awareness, but over-reliance will also create an illusion of the actual position of the muzzle (because the laser is not fired from the muzzle, there is no point when the muzzle is blocked). These two problems can only be solved by adequate training. So the laser sight does not mean where to hit.

The most common scene in the movie, "the light spot shines on the center of the eyebrows" is very funny in reality. Unless the target's eyebrows are unbiased and just at the zero distance, because of the holdover, when the laser spot scope is on the center of the eyebrows The bullet will definitely not hit the eyebrows. In reality, the simple way to overcome holdover is to prioritize the center mass of the target to minimize the impact of aiming errors. Moreover, due to the confusion and interference between the laser aiming spot and the optical sight (such as the electronic red dot sight), the two are actually used at the same time as possible. Most FPS games do not correctly simulate this basic optical and perspective principle. Because of the difference between the installation position and the zero return method, if the two are used at the same time, when aiming at objects at different distances, the laser spot will keep jumping in the sight of the scope.
This has a great impact on the concentration of fast aiming. I don't know if anyone can overcome adaptation by training. A sniper aiming at a laser spot in a literary work is even more performance art. Therefore, the use of laser for shooting aiming has many limitations, but it also has many advantages. On the one hand, it does greatly shorten the "search-aim" conversion time, and on the other hand, it provides a relatively reliable alternative to traditional sights because of the inconvenience of wearing night vision goggles, gas masks, and bullet-proof masks.

In short, the use of visible lasers for light weapons aiming is quite special and not necessary. Generally, civilians who conduct self-defense or military police who specialize in indoor assaults consider using it when the light is not strong. However, on the battlefield in recent years, it is more common to use laser pointers in the invisible light band represented by US military equipment (mainly infrared bands, of course, most of them also have the ability to emit visible band lasers). The more representative ones are AN/PEQ-2A, AN/PAQ-4 and AN/PEQ-15. Lasers in the infrared band are invisible to the naked eye, but can be observed by infrared optical devices such as night vision goggles.
(The multi-function laser pointer commonly known as "pec box" has been very popular in the frontline troops in the AN/PEQ-15 era, and almost everyone has a gun. This kind of "advanced" optical equipment and night equipment is more expensive than two rifles. Sights are also a high price to maintain technological superiority.) AN/PEQ-2A was not equipped very late in the US military, but at that time, like optical sights, night vision equipment, and radio, they were one of the few in the rankings. Large pieces, equipment scale and density are still very limited.
The aiming for light weapons is also slightly extravagant, and it is mainly used to instruct targets to guide the firing of machine gun positions and armored vehicles. After the infrared light under the night curtain is enhanced by optical instruments, a bright ray is formed along the approximate extension of the muzzle, which is far clearer than the visible Hunting Laser Sight Scope under the naked eye, and can be clearly distinguished from hundreds of kilometers away. With the popularization of the relatively inexpensive AN/PVS-14 and 15 night vision devices, the proportion of infrared laser pointers is getting higher and higher.
Although there are still some disadvantages like visible laser aiming, as "advantageous technical equipment", its functionality is extremely extensive in asymmetric operations. Not only can it easily indicate the target and improve the aiming problem when wearing night vision equipment, it can also help distinguish the position and orientation of friendly forces, enhance the awareness of muzzle safety, and help control the formation of the team. AN/PEQ-2A and AN/PEQ-15 also have an "infrared headlight" function that emits infrared illuminating light to improve the observation ability of the night vision device.