> it is not true that when you ask those people to do otherwise they simply pretend to have done it and forget you asked later.

I had a coworker that more or less exactly did that. You left a comment in a ticket about something extra to be done, he answered "yes sure" and after a few days proceeded to close the ticket without doing the thing you asked. Depending on the quantity of work you had at the moment, you might not notice that until after a few months, when the missing thing would bite you back in bitter revenge.