Tell it to the Hollywood casting directors who insist on using an aging male actor, but insist on a younger female costar. They just refuse to write decent roles for women between the ages of 40 and 60, so American actresses disappear. The Brits don't do it - Judi Dench continued acting through her 40s, 50s, 60s, 70s. . . So did Maggie Smith, Gemma Jones, and others I can name off the top of my head.

Tell it to the movie-going, TV-watching public. If viewers would stop supporting this nonsense, they'd stop producing it.