Why Doesn't Laser See White Hair?
Laser hair removal devices target dark hairs and heat and destroy the hair root. However, since there is no melanin in white hairs, the laser light cannot detect these hairs and since no heat is generated, the hair roots are not damaged.

Alternative Methods to Get Rid of White Hairs
If you want to get rid of your white hairs, you can consider the following methods other than laser:

Needle Epilation:

This is the most effective method for white hairs.
Each hair root is given an electric current with a thin needle and the hair root is destroyed.
It provides permanent results, but it is a process that requires patience.
Electroepilation:

This is an advanced version of needle epilation.
It can be preferred for faster results.
Cream or Wax:

It is a temporary solution, but since white hairs are not suitable for laser epilation, it can be applied regularly.
Conclusion
Laser epilation is not effective on white hairs, because the laser light acts by seeing the color of the hair. If you want to get rid of white hair permanently, the most effective method is needle epilation. Before having laser epilation, it would be best to consult a specialist to determine whether your hair color is suitable.