The San Paulo metro is modern, and so far what I have seen of it is safe. It is not idiot-proof however, and I made a number of bone-head mistakes.
I took it in the morning around 7:30am, intending to go in the direction from Moema to Borbogata, which is four stops on the Lilac line. The Metro here on the Lilac line is clean. The platform has a safety wall with sliding doors, unlike the Metros I used in DC. The crazy incidents you hear about where someone pushes a person in front of the train can’t happen here.
Bone-head mistake #1. I didn’t notice that I was the only person not wearing a mask. I don’t think anyone was staring at me, until I was approached on the train by a guard who said things in Portuguese that I mostly did not under except when he pointed to his face and said “Mascara”, which really didn’t require translation.
Bone-head mistake #2. The way I normally use a Metro is to study the endpoints and make sure I choose the correct endpoint, which defines the direction of travel. Today, for the second time (!), I mixed up the endpoints, boarding the train heading in the exact opposite direction. So now, four stops became twelve, the first four being in the wrong direction, the next eight (now in the correct direction) making up for the mistake and advancing me to the final destination, which is Borbogata.