Older drivers fail to follow the rules of the road sometimes. This includes the failure to back up without looking for any objections, yield the right-of-way, and forgetting to signal when changing lanes or turning.
When driving around an older driver, even if they seem like they are driving normally, take precautions. There could be a moment where they have a stroke, or a sudden medical condition where your safety is at risk. It is important to take a slower approach when driving behind older drivers. They may be driving slower than others but it is not to annoy you, only to keep their safety and protect others on the road.