Ignorance IS possible though. I've heard both used interchangeably my entire life. Lots of people are never told that it's wrong to use 'Indian' or even 'American Indian'. I myself didn't learn until probably a year or two ago. Heck, Montana state code uses the term 'American Indian' in many places and I'm pretty sure (though I can go check if you wish) that Native representatives in our Legislature haven't yet introduced legislation to change it. I'm also quite certain such language would have passed with minimal, if any, opposition, since MT has historically been a state in which local government is usually Democrat (the wave of Californians moving here has drowned us in red, but that's a phenomena less than two years old...).
Anyways, I'm just telling you what I know to be true because, quite simply, it is...