It happens a lot more to people who don't know the rule.

I've definitely seen it, and I have never played a ton of chess.

More common in blitz. Carlsen executes it in the 2013 world blitz championships I believe, and I've had it done to me and I've done it as well in 1m/2s games.

Even if it doesn't actually happen, it often impacts play, especially in the end game.

It's relevant in almost every game, if you include variations that you have to consider when deciding your move.