The power levels are just too low. Wifi routers are a few hundred mW at most, it drops off rapidly with distance (inverse square law) and a person will only be hit by a fraction of the total 360° field. If you think microwatts of non-ionizing radiation are killing you, stay out of sunshine as it's much, much worse. I could see this potentially being a problem for workers on cell or radio towers but at everyday levels it's harmless.