Why do many people spit on the ground?!

[Winston]

I don't understand something. How come everywhere I go, a lot of people are spitting on the ground all the time? This is especially true in the Philippines, where even girls do it. As a result, when you walk on streets here, you always see spit wads on the ground, which makes the PI look even more ghetto. Yuck. Sick.

What's up with that? It's so gross and uncivilized. One time a Filipino guy spit on my shoe when we got off the bus to Sagada to pee. When I got angry and said, "Dude, you spit on my shoe!" while I was wiping my shoe against the grass, he apologized.

I've seen it in Eastern Europe and Russia too. Why do people do that? What the hell is their problem? They can't all have phlem from a cold. Many of them do it casually all the time, like it's some habit. It's disgusting. What the f**k is their problem? People are so gross!

Is there a logical explanation for this unnecessary gross stupid habit?