"Maturity" isn't that clearly defined. Ask 100 people, get 100 answers. But in everyday speech people often use it to have to do with your conformity to arbitrary notions about what your preferences, beliefs, ideas, values, behaviors, etc. should be at different ages even when these things are inconsequential to other people's well-being or to your responsibilities.
Responsibility, compassion, those things are important but the concept of "maturity" is too vague, nebulous, and covers a lot of things that are irrelevant(except in circumstances where you want to trick the person into seeing you as more mature).