I was of course being facetious with my comment. That said, I tried asking Gemini just now ("show me some images of typical American firefighters"), one of them was this. A fair few others included black firemen, which likely reflects the reality of American city firefighting.
It's not quite a one-legged lesbian, but it's also not exactly all White. I do have to clarify that I've been asking Gemini for ethnicity breakdowns quite a lot recently, e.g. criminality in the UK.
I then asked Gemini to explain whether this photo represented the reality of ethnic diversity in firefighters, and it said this:
"The reason image searches for professions like "firefighter" often show predominantly White males is due to a combination of historical representation, current demographics, and biases in the data used to train image retrieval algorithms.
Here is a breakdown of the contributing factors:
Actual Demographics: In the United States, firefighting is an overwhelmingly male and predominantly White profession.
As of 2023, data shows that around 95.4% of the firefighter workforce were men.
Regarding race, approximately 79.1% of the firefighter workforce were White in 2023. This is higher than the percentage of White workers in the overall protective service occupations category.
While women and racial minorities are actively working as firefighters, the high percentage of White males in the profession means they naturally make up the majority of real-world images available."