"Let dad do whatever he wants and stay quiet" or
"throw out suggestions, or a sound argument to convince him to see things MY way"
So yes, in a way, your kids are in fact "letting" you chose how to spend your money if they say nothing. Otherwise, whether your pride lets you admit it or not, they can heavily influence your decisions toward them.
As far as your assessment on teens, it's mostly correct. I just believe in giving everyone a chance. He seems to have his head on strait (as he asked for recommendations and help, rather than just whining), and hopefully he won't do anything stuipid (an possibly raise insurance rates on the car even higher).