[forgottenpaswrd]

Because it takes serious effort to do it.

I'm glad they did it. 3 dollars is nothing compared with the value I got from being able to use python on my phone.

[sanxiyn]

I grant that "Python for iOS" took serious effort, but I am sure "Python" took more effort. Still Python is free.

[Tycho]

Python is free because the creator wanted it to gain traction. This app costs money because the creator wants to charge for it. No other considerations are relevant really.