Well, let's face it, the information was out there, if she'd cared to look. A quick glance at the British newspapers during the brief months of their courtship would've shown her what the senior royals spend most of their time doing, whether at home or on foreign trips.
The thing I've always found strange was that I always saw MM as a type A personality; someone who always comes well prepared, done her research, knew what to do/where to go etc but for some reason when it came to the Royal Family she seemed to do absolutely NOTHING to help herself. She didn't take it upon herself to learn the national anthem, or research what jobs the royals do, she didn't seem to understand the hierarchy of a monarchy, or any of the basic stuff that any normal person would quickly Google.
Some of this can be down to cultural differences, others perhaps due to Harry not helping her, but there's so much that I just cant understand why she didn't even TRY to help herself. Has anyone ever explained why she turned down Sophie's offer of help? For someone who claims that the Royals were stand offish, she didn't seem to embrace any help/support that was there for her.