No way can I use a touch screen, especially on an 'i phone', due to my knackered fingers.
In fact, it could be downright dangerous - I'd probably end up launching an ICBM from somewhere to God knows where !
BTW.. it is not fault of computers. Just there hasn't been born a programmer yet who could write a computer program that would be idiot-proof at 100%. There can be always found an user who hits a such combination of keys causing a system/program crash..
Saw a bug report from Microsoft once, the title was: "Holding the F1 Key down for 11 hours causes system error." I remember thinking someone got paid to do that! As a corollary we received a report on one of our programs crashing after a user performed a certain set of actions. The programmer in charge of that area said to tell the users not to do that again. Problem solved.