His brother was very critical of his driving
Why was he so critical of his driving?
Because he was a bad driver. He lied and told him he was a good driver though.
He wasn't a very supportive brother! He shouldn't be so critical of his brother's driving. He probably makes his brother more nervous to drive.
They are both irrational though.
You are right, it is hurtful to criticize each other. Siblings should support each other and be there for each other. They could become better drivers by working together.