Why condom not 100% safe? If penis inserted into vagina with condoms on for just 2 minutes, will it spread the virus? Chances of such way infection?

Is anything 100% ?? A condom is not 100% effective in preventing infections because a condom only covers the penis, but not any part of the woman, and not other parts of the man's skin that rub on the woman. It is not 100% effective in preventing pregnancy because in the heat of the moment, mistakes can be made, allowing sperm to accidentally get into the vagina. If one is ultra careful, he may come close to 100%.
Other skin. Nothing is 100%. People have foreplay and skin to skin contact before applying the condom. There are areas of skin that touch that are not covered by a condom, a condom can slip off, or rarely break. All these things are a way for there to be less than 100% effectiveness.