I think the issue is NOT the ability to understand, but the WILLINGNESS to understand. My parents were not good communicators with their children because of how they learned discipline in their family. Instead of being so 'GOOD' keeping quiet, I should have let them know that we needed to talk. The trouble is, ADULTS don't understand the need for PROPER and EFFECTIVE communication. It's truly amazing, I've seen it all my life. As we grow older into adulthood, we develop other concerns with daily life and become less and less of a communicator and learn to be inconsiderate and less sensitive to other people. We learn to be condescending to whoever we think will let us get away with it. It is usually the people closest to us who UNINTENTIONALLY mistreat us. If only they knew of their effect on us, they would probably be more gentle and caring about our feelings.
Maybe you could explain to this to them (they will thank you for letting them know).
(But remember, you are more precious than the gold at the end of a thousand rainbows to them, and they grow older with worry every time you stay out late, but they don't want to stop you from enjoying life).