That would be because they don't understand what fascism is. The unfortunate result of internet colloquialism.

Look up the definition of fascism. There are a few. Here is one:

Broadly, a tendency toward or support of a strongly authoritarian or dictatorial control of government or other organizations; -- often used pejoratively in this sense.

What do you call it when the American government supports and imposes strongly authoritarian or dictatorial control of government even if in another country. Is that not fascism?

We did this in Guatemala too at the behest of the United Fruit Company. The CIA director Allen Dulles and his Secretary of State brother, John Dulles, were on United Fruit Company’s payroll for 38 years. In 1954, the CIA overthrew the democratically elected government of Guatemala after they passed reforms to end exploitative labor practices by United Fruit Company that it saw as a threat to its profits.

Another definition of fascism involves the repressive use of government by business to ensure control of the market.

A political regime, having totalitarian aspirations, ideologically based on a relationship between business and the centralized government, business-and-government control of the market place, repression of criticism or opposition, a leader cult and exalting the state and/or religion above individual rights.