Is there a word or short phrase to indicate the assumption that someone in a position of authority is correct?

My partner is writing a reflective essay that outlines an incident where she had questioned something that someone was doing and they disagreed, and because they were more senior than her, she assumed that they knew what they were talking about, so didn't push further.

Is there a word that or short phrase that encapsulates this meaning?

The phrase you are looking for is the Authority Principle / Principle of Authority

The basis of the principle is:

If an expert says it, then it must be true

Indicators of Authority examples:

• Uniforms

• Wealth

• Power

• Physical attributes

• Attitude

I believe you are looking for a single word. One possibility would be "deference" -

Polite submission and respect: ‘he addressed her with the deference due to age’

Phrases:

'in deference to'

    Out of respect for; in consideration of:
    ‘in deference to her wishes we spent two weeks on the coast’

Oxford Dictionary