> Oh no, you need to find a line of text in a string that contains the word 'YES'. How incredibly difficult. Are you even a programmer? This is entirely trivial.
"Yes alright renew my subscription, just make it start in two weeks this time"
Your "solution" fails immediately here, because it gives people a false idea that they are in a dialogue with you whereas they are actually just expected to reply in a binary way.
Finding "a line of text in a string that contains the word 'YES'" is indeed trivial, however if that's all you can think of you should not be employed in any position of responsibility as it demonstrates a profound lack of judgement, understanding of how real people behave, and general business acumen.