In other words, most people do not spend their entire lives in one place anymore because they have the ability to transport their belongings with ease. For example, before the advent of cars in the US, people found it incredibly burdensome to move from their hometown because they had to carry their belongings or load them up on wagons. In contrast, most people these days move several times during their lifetimes and often end up in a completely different city than where they were born.
Most of these people relocated with automobiles, not with airplanes. Therefore, cars have had a greater effect on society because they have facilitated the relocation of so many members of society. In addition, another reason why cars have had a greater effect is because they are used much more regularly than airplanes. To be specific, in most developed parts of the world, automobiles are used virtually every day not only to transport people, but also to transport goods from place to place.
For instance, most people in America drive a car or ride the bus every day to get to where they need to go. Cars and trucks are also used to haul cargo from city to city. Conversely, the vast majority of people probably get on a flight only during special occasions like vacations or holidays. In addition, besides mail and packages, few goods are transported by airplane. Thus, cars have had a greater impact on society simply because they are used so much more frequently.