People who often say "I'm sorry" could fall into one of the following categories.
First, they could be sarcastic.
Such individuals should not be considered human.
Second, they could be overly polite.
This kind of apology initially feels acceptable, allowing one to sense the friendliness of the other party, but constant repetition can create a sense of inapproachability and detachment.
The third type is like Xiao Shen.
A little self-deprecating pitiful soul.
She would quietly apologize to her mom, to the rehabilitator, to herself, every time she felt powerless and thought she might burden others.
This is normal. Even if one does not have a people-pleasing personality, feeling unable to give back equivalent value can lead to the feeling of letting the other party down. And if one constantly causes losses for others, anxiety from the inequality of exchange will eventually arise.