Why didn't anybody tell me??

For three months, I have been dutifully fulfilling my two-part daily commute to and from school. From home, I must walk to the subway station (about 5 minutes), ride the subway two stops (5 minutes), then transfer to the green bus for another 10-15 minute ride which takes me to school. Most mornings and afternoons I patiently wait anywhere from 10 to 30 minutes for the green bus to swing around the corner to pick me up. I have been told that the green buses are the ones that may or may not come. The blue buses are the reliable ones. Unfortunately, I don't need the blue bus--I need the green one. Well, last week, I got off the bus, on the way home from work, at the subway station only to run into a couple of my coworkers. One man, Mr. Kim, the funky art teacher, told me that he had walked from work. Well, my eyes flew open and I started firing too many questions too quickly for poor, very limited English speaking Mr. Kim to keep up! So, the next day, I asked him if I could walk with him after school to learn the way. He has been faithfully waiting for me each day since then to walk with me to the subway station. Each day, we time ourselves and it takes about 12 minutes. MUCH faster than the bus! And, I have a new friend! I know few things about this Mr. Kim, but he is very friendly and now greets me each morning with a cheerful, "good morning Bonnie teacher!" My question is: why didn't anyone explain this to me when it was still warm enough to walk outside without risking frostbite??