Even without thinking about it, you would know that being administrator of an estate is a pain the neck. You are likely grieving the loss of someone you love, yet have to clean up legal issues left at death. It is not easy even if the family gets along, the debts are small, and the property is simple. It can be a nightmare if there is conflict.
Let's suppose you lose someone you love, and no will is found. You find that your siblings do not have the time or energy to take care of the estate, so you file a "petition for letters of administration" with the probate court. That includes getting a bond for yourself worth roughly the value of the estate and advertising the opening of the estate (to invite the creditors and troublemakers to appear). Once you are appointed, you take inventory of the assets, prioritize the bills, pay the bills from the assets¸ distribute the remaining assets (or ask the court to declare the estate insolvent), and eventually close the estate. Most people who do it once don't do it again.
Nonetheless, if you see that you are the best person to take care of your mother's, father's, or sibling's affairs, you will likely do it, and for the best of reasons. A man once observed Mother Teresa cleansing the filthy sores of a leper and said: “I would not clean him for all the money in the world." To this Mother Teresa replied: “Nor would I.”