First of all, HPV infections are usually asymptomatic, so most people don't know they have them, except for those with visible genital warts. Second, 50% of women (and presumably men) are infected by one or another type of HPV within three years of becoming sexually active. If you wait until people become sexually active it may be too late. The ideal time to vaccinate is pre-teen.
Which is why those who are sexually active, symptomatic or no should get the vaccine.
Those who are not sexually active yet should not get the vaccine. They are 100 percent immune from getting HPV.
There are reports of young girls who have died from the vaccine. It’s just not worth inculating those who are not sexually active.