Probably because you don't wash your hair
No actually it's good not to wash your hair when you have lice because they like clean hair... when I was younger I had lice and a lot it toke me a really long time to get rid of it but one day I went to the doctors and they gave me extra strong lice remover they gave me about 4 so I put 2 that day then I put another 2 seven days later and voila gone! And I know too buy lice removal is expensive but idk 😂
Get a prescription, nix from walgreens, dye your hair, or cut it. Dont pass those buggers along. Boil your hairbrushes, wash your sheets and pillow cases, put your stuffed animals in the dryer. You need a lice comb to keep combing out the eggs and nits or youll never get rid of them.