My pleasure

[casino]

A native speaker says that “My pleasure” meaning
“You’re welcome.” can be used only in an equal relationship.
I would like to know if this is true.

Casino

 

[Copyright]

No, it's not. I can say it to the seven-year-old whose bicycle chain I slipped back in place in response to a "Thank you."

 

[perpend]

It's complicated, Casino, because of different cultures trying to use "English".

For me, in American English, these could mean the same thing:
-- You're welcome
-- My pleasure

I don't perceive a huge difference. I would like to think most relationships are "equal", so I think something is getting Lost In Translation, no pun intended.