The thrift consciousness of the elderly is the most fundamental reason for their behavior! In the last century, the elderly generally experienced a very hard life. When they are young, their life is usually very difficult. Most people have their last meal, and there is no next meal. It is wishful thinking to have enough food every day. Therefore, such old people generally form the habit of thrift when you are young, and will keep this habit when you are old!
And now many elderly people in cities don't pay by subway or bus! Many old people think that they don't have to pay for the bus anyway, and they always take the bus to far away places to buy something for a few dollars! But in fact, this practice is very inappropriate. Old people should be grateful when they enjoy "special treatment". What they should do most is not to seize resources from young people!
Finally, young people may do this to exercise! Imagine that after retirement, the elderly generally do nothing, and their free time naturally begins to increase. Not only do they not have to spend money on buses, but they can also go out for a walk and exercise more. This is a "steady profit without loss" for any elderly person, so they are "keen" to do so!