What do we call the system of using buses and trains instead of personal vehicles?

The system of using buses and trains instead of personal vehicles is referred to as public transport reliance. This term emphasizes the dependency on shared transportation systems that are accessible to the general population. Public transport provides an efficient means of moving large numbers of people within urban areas, helping to reduce traffic congestion, lower individual transportation costs, and decrease environmental impacts associated with the use of private vehicles.

In contrast, private transport use refers to the reliance on individual cars, which does not align with the concept of public transport. Active transport methods involve non-motorized forms of transit, such as walking or cycling, which also differ from bus and train systems. Carpooling is a strategy to reduce the number of vehicles on the road by sharing rides among individuals, rather than using a structured network of public transport. Thus, public transport reliance is the most accurate and relevant term for the system described in the question.