The city's public transportation system has invested significantly in improving the frequency and reliability of bus services. Advocates argue that this enhancement will lead to a greater number of residents opting to use public transport, thereby reducing traffic congestion and pollution levels. However, a recent survey showed that a large percentage of residents still prefer using their own vehicles even for short trips. Critics of the public transportation improvements believe that simply increasing bus frequency is not enough to change commuting habits.
Which of the following, if true, would most seriously weaken the critics' argument?