We will be presented with a complex situation in an incredible short period of time in the worst possible conditions and then be asked to perform with pristine responses. Look at self-defense in a real logical light. You will never start the process. You will be handed a potential threat and then have to deal with it. No surprises take place in target shooting.
Nobody moves the target or turns out the lights.
Nobody will kill or hurt you for failing. Target shooting is based on the best conditions. Imagine if you had to know all the possible information about your PC and as you use it the PC can ask you constant questions that are complex and if you don't respond correctly it shuts down. Imagine if your PC could lie to you and cheat you in the process. That is self-defense.