Why don't companies recruit people under the age of 18?

According to the Labor Law, only citizens aged 16 can work, and those aged 65438- 18 are underage workers. According to the regulations of underage workers, they are not allowed to take part in heavy physical labor, work overtime or engage in work with toxic substances, and they have to undergo physical examination every year to confirm whether there is any physical or mental injury, so many enterprises do not recruit employees below 18.