Joe Average will take the train if it the cost compares well with driving. If going to a city with a lot of traffic, horrible roads to navigate and scarce and/or expensive parking, and there is a rail service which provides a shorter journey time door to door and the fares are no more than the cost of fuel and parking people will take it.
If going to the next town over, the start and/or destination is some way from the station and it runs only every hour and there is free parking, Mr J Average will drive unless he is planning to have a few jars.
It is why the idea of a railcard for all needs to be pushed as it will bring fares to be closer to the cost of a car journey + parking. As has been wisely said before, fuel duty freezes give a false sense of economy in running a car. The ticket price may be the same as the fuel costs but rightly or wrongly, the costs of maintenance per mile do not enter peoples heads.