Nope, nothing to do with school. Just with ornitology, habit and, the most important, speed
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Ornitology, because that is not my specialty nor one of my main interests, so in some cases by chance I can be very precise because by luck is a bird I know well enoug, in other (most cases), I am very broad of even very generic. I am sure I had seen flamingos in some documentaries about parts of Africa when I was younger, but it was not the first thing I thought about.
I lived in two countries where apparently at a check a small bit of the country has also some Flamingos at least moving through, and even visited the region in one of the two countries, but did not have the opportunity to see them "live" - at least in one case, I know a bunch of people from at least one of the two areas, and even them, never mentioned having seen any flamingo, it seems it is not really something seen so easily (though ancients did eat them and considered them a prelibacy).
I suspect you think they are more diffused in the World than what they are.
Habit, because I am used to the habit of people using (plastic) ducks(-themed) stuff when taking a bath or in a pool, so that was the spontaneous association, through is true that if I had wanted to be more precise (though still not precise enough for you ;-)), I would probably have gone for cygnus, in this case.
Flamingos are not present where I grew up, cygnuses also have a long neck, and are associated with beauty, grace, and swimming - it is true that cygnuses are not that flamboyantly coloured, but that kind of floating device is not meant to be a fully correct reproduction for a museum, so the colour in itself for me means nothing :-D.
Speed is the most important, because my interest was in the overall picture and other characteristics, and in typing a fast post, not in doing a precise identification of what species of bird was being represented, I did not bother looking to much at it or checking - life is about priorities ;-)