Do singers need to read music?
No. Many good singers learn by ear, and in pop, rock and folk that is normal. Reading music helps in other ways: you learn songs faster, you can sing in choirs and ensembles where parts arrive as sheet music, and you understand what you are hearing. A little goes a long way. Knowing which line or space is which note and how rhythms are counted covers most of what a singer needs, and it can be learned a few minutes at a time.