A2 En, dans, de etc etc.

You‘re making it sound harder than it actually is. Female countries are those that end in -e. They are the majority and all work the same (with some very few exceptions). Male countries also work the same as a group. The lesson makes it seem like a lot to remember but it really isn’t all that hard. 

To the second part of your question - yes of course the French make mistakes and don't necessarily know the gender of every noun without fail. On the other hand, they will also often correct themselves, or you, when an error is made. It is worth looking at the exceptions and deciding if they are pertinent to you - for instance although I do know the Texas/New Mexico/Quebec 'exceptions' now, I didn't really try to learn them directly as they are not areas of regular interest to me.  There are other lessons that support the base knowledge on this subject eg Continents/countries/counties/regions/states are masculine, feminine or plural in French (Gender)

Love the quote about General de Gaulle! We all need a good laugh - it's important for us to have a sense of humor while learning another language. So many countries and counties - so little time to learn them all. LOL!