I think there is this normal developmental phase where teenagers reject their parents in order to be able to fly the nest. DS just hasn't reached it so far.
He trusts us to put him first when offering advice and to make a real effort to think about it first and then give good advice. (i.e. what pretty much 99% of parents do but many DC won't believe it because they are going through that transition).
DS1 does believe us though and it makes our relationship really harmonious as he just waits for us to tell him things are his choice and to offer to help him. He's been like this since he was born - he was a really contented baby because he seemed to expect us to look after him, so he rarely cried.
I think (sort of hope, sort of dread) he'll start to reject us eventually, but there's not much sign yet, so I expect he'll want our views about choosing a university.
By contrast, DS2 is already of the mindset that everything we say or think must be based on old-fashioned ideas and therefore plain wrong.