A lot of federal money goes to state and local health programs. For example, consider mammograms. A state will be given a budget to spend on mammograms. The state doesn't do those screenings itself, so it solicits bids from several healthcare organizations. Those organizations create proposals with estimates of the number of residents eligible for free screening in their area, the burden of breast cancer among that group, and whether those potential patients fall into underserved or high risk demographics. All of that comes from high quality data published by the federal government. Those groups pull data from these online data sets.
Your grandma might have gotten free mammograms because of that data.