Why do people ask "how are you?" Or "how was your whatever holiday just occured?"

I'm asked this by cashiers and other random people I have to interact with and I'm always wondering what do you wanna hear? The truth? (For reference I'm an introverted socially awkward 33 year old caregiver who works with hospice/end of life clients)

Sometimes I'll be honest. "Well, no one died today" or "well, nothing bad happened (said with a smile on my face) or the lie. "I'm good" (said with tears in my eyes and a fake smile)

I really wish people would stop asking this, you assume I want to interact with you more than necessary?

Do you ask cause you want to know? Or cause its expected as a social norm? Or maybe to break up the monotony of your job? Or maybe you don't know?

Why do YOU ask?