As an American I knew from the start that the line of succession was controlled by Parliament. You can't be told about the monarchy in much depth without learning about primogeniture and laws passed that effectively decided who could or couldn't sit on the throne. And I think there was a documentary a few years back, King Ralph, that poked a bit of fun at how absurd that might get.
But I think Americans generally have a poor understanding of the role of titles and positions in the aristocracy and how those interact with lawful succession. I remember hearing once that the ascending monarch's titles are all extinguished such that no one title is said to lead to the crown. Hence every Prince of Wales must be created anew. But the whole notion of creation and extinction of titles and their heredity just sounds to Americans as an undifferentiated and unimpressive cloud of dukes, princes, barons, earls, viscounts, marchionesses, monsignors, thanes, and elderberries. As my spouse said while watching the recent coronation: "I thought we fought a war so that I didn't have to remember any of this ◊◊◊◊."
What unites them all in the American view is best summed up by Dennis of the Moor: "And 'ow did you get that, eh? By exploiting the working class." That is, a perpetuation of a class of wealth and privilege by institutional means, largely maintained by and for the benefit of various Upper Class Twits. Eventually one of them gets to be king. But exactly how is murky to us, as soon as it falls outside the rules of straightforward primogeniture. It never occurred to us that Andrew is somehow in the line of succession.
The delicate ballet amongst styles, titles, and succession is largely lost on us too. The king can apparently take some of those away just by announcing it from the balcony amidst a fanfare of trumpets. But others can only be taken away by Parliament. I'm sure most of us naturally thought that the king stripping some of that privilege away from Andrew automatically withdrew him from the line of succession (even if he is only eighth in line and would probably require a King Ralph level of catastrophe to make him heir apparent—or presumptive, however that works). A lot of us thought that you have to first be prince of something in order to eventually be the king of anything. Most of us are just hoping we don't have to face the prospect of Don Jr. ascending the throne of America upon the death of our own Baron Harkonnen.
But even here in America there is the sentiment that even the credible suspicion of wrongdoing ought to be enough to remove a person from an otherwise undeserved position of privilege. It doesn't always happen. But there once was a time in the U.S. where credible suspicion of lawbreaking meant you had to fall on your sword and resign any offices of public trust. So it won't come as a surprise at least to some of us if Andrew is fully removed from his privileges before any actual legal finding issues forth.