Final answer:
A model car is not a form of public transportation, whereas trains and airplanes are both widely used in public transit systems.
Step-by-step explanation:
The form of transportation that is not a way of public transportation is a model car. Trains and airplanes are both commonly used as public transportation. Trains have been a critical part of infrastructure to connect cities and for transportation within cities, often operating on electric power supplied through wired systems like overhead lines or third rails. Airplanes, while largely dependent on fossil fuels, are essential for our global supply chains and for high-speed travel over long distances. Despite discussions on electric and solar-powered vehicles, such as solar-powered aircraft or electric cars, these technologies have not yet become viable substitutes for traditional planes and cars in terms of public transportation. The model car, while it can be electric or even solar-powered, remains a demonstration rather than a practical mode of public transit.