I can't comprehend why, given they had plenty time to prepare and Oprah was never going to ask any difficult questions, why they answered falsely.
For example:
M: a few days before the wedding we had a practice ceremony in the garden with the archibishop. The sun was shining and it is was prefect, just me and Harry. That feels like my real wedding.
On the passport:
M: I've spend my last 15/20 years being in charge in my own life - if I wanted to jump on a plane to Paris I could. Now I don't even have my passport, if I want to go anywhere I need to get it checked out, get security etc.
On the curtesy
M: I couldn't believe they did it in private, I mean yes, I thought it was all just for show, didn't everyone.
On the colour of her baby:
M: well no I wasn't there, Harry told me. Maybe it was meant as an innocent comment, but Harry was raging.
She had every opportunity for the public to 'take to her. Explain she was shocked by the strictness, security and although Harry had told her, what a shock it was and she wasn't happy. Her mental health had suffered. Harry wanted to make her happy and they couldn't see how she could be happy in that environment.