I feel your pain!
I DEFINITELY see "age discrimination" at work in the state agency I've worked for the last 21 years.
In two ways.
In one way: young applicants do better than older applicants. There is a tendency here the last four years to hire the most attractive applicants, believe it or not. The former regime was one of dirty middle-age-crisis men, and they hired a bevy of beauties regardless of qualification or experience. (Human Resources staff that advised them against this trend were released). The current regime is a spin-off of that and the trend continues, with some attractive young men added to the rosters.
The other way: age within the agency: there has been a deliberate attempt at this agency to remove all senior workers for various reasons that I won't go into here. As a result, with downsizing of over one third over the last four years, a large number of these employees "released" were employees with long tenure. I believe that there are less than a dozen employees now that have fifteen or more years of service, and they are not in important managerial positions. There are not more than two dozen of 425 that have been with the agency between ten and fifteen years. It has really meant a lot of organizational/professional knowledge gone literally out the door, and has been crippling to the mission and its execution. A pity indeed!
And no, I don't want to be interviewed etc. It wouldn't be healthy.