A number of factors prevent a person from working up to the age of 75 and result in a drop in income well before then.
For example, as you rightly said, a number of seniors must leave the workplace not by choice, but because they become family caregivers. They leave the workplace to take care of their spouse or loved one. Their income drops significantly.
Of course, providing financial compensation to seniors aged 65 and over would certainly meet the needs of a larger portion of the population.