The lesson for planners and government here is clear: combine free transit with measures to make it massively more incovenient and expensive to own a private automobile.
For less dogmatic people, it may be useful to reflect on what else needs to be done to make public transit useful to more people, beyond the price.
How did you make a jump to that conclusion? Correlation doesn’t mean that it’s a sole reason (or even one of the reasons)
This could be because making transit free reduces the underutilization of large mass transit systems.
... the market will regulate everything. /s