I would probably think that the erection of signs and advertising material on public or private land for the primary purpose of advertising or promotion, would constitute development activity under the Environment Planning and Assessment Act 1979. Development consent for this activity should be sought. If not then fairly hefty fines can be imposed.
Contact your local council. If you state your concerns …. the signs are a nuisance, a hazard, a hazardous distraction to drivers, an obstruction, are blocking access etc etc and take photos of the signs then the Council should be able to issue infringement notices to those businesses.