400-500 players and the Sicilian

I'm rated 455 at the moment and most of my opponents are within 100 of that range. I always open with e4 as white, and in my last 20 games as white, only one opponent has used the Sicilian defense.  Is this is a statistical anomaly or is it just uncommon among low rated players? If it's the latter, why?

I think it's just that 1..e5 feels more natural to beginners. In fact, I see many beginner to intermediate players complain that they almost never get to play their preferred opening because the opponent goes out of book so early. I have mostly played Daily chess, so people tend to stay in book for longer.

The sicilian defense is uncommon among beginners because it should be. It has lots of theory. e5 is a good move because it does three things - Controls the centre, makes way for your bishop, makes way for your queen. And afterwards all you have to do is to develop the knight then the bishops then castle.

e5 can have a lot of theory as well. For instance 2. ...Nc3 lines have a lot of possibilities, lines of Ruy Lopez are really numerous. But in any case, theory is not that important for a beginner, and even an intermediate player (but especially a beginner).

For instance if you play 1. ... c5, people will often play 2. Bc4, which is not great but it is (one of) the most common second moves vs Sicilian defense on lower levels. So what good is theory, when pretty much all Sicilian theory goes out of the window on move 2? 

In any case, it is completely fine to play Sicilian on lower levels. You might lose horribly some of the games in the open Sicilian (surely not all) until you start playing better, but if you play your cards right, you will win many games vs 2. Bc4 which you will get on lower levels. So if someone likes playing 2. ...c5 and slowly building his opening knowledge with the game analysis (and after some time some opening database), it is completely fine to play 2. ...c5.

Never play sicilian unless youre very high rated. theres waytoo much theory just go for a different opening with less theory like the caro kann

that goes 1.c6 2.d5

I am doing it pretty much since the beginning (I did play some 1. ...e5  as well at the start but very rarely) and I am completely fine. White doesn't know theory either at 400 level, you will be on a level playing field.  Nothing wrong with Caro Kann either. Of course, I don't say that playing Sicilian will give you some great advantage, I am just saying that if you want to play it, it is completely possible. 

Its just that sicilian is so imbalanced that beginners will find it harder to not make bulnders

That is true, it is imbalanced. But it is imbalanced for the opponent as well.  Blunders will happen often on that level whatever opening you choose. I've checked, I've played exactly 3 1. e4 e5 games (one was against a bot when it was possible to play bots in live games) before switching to 1. ...c5. I played a few afterwards, but in the last 6-9 months I think I haven't played a single response to 1.e4 other than 1. ...c5. Of course, not everyone will like it.

But in any case, whatever opening you choose, I would stick to it and build it slowly and steadily. I wouldn't switch it too often unless you really hate it. 

play the kings indian as black because you avoid all early opening traps that your opponent might know

I won't lie: the only reason I play the Sicilian defence is because I like the name. Am I a bad person? Haha.

no its the same for me and the monkeys bum so i cant say much

No statistical anomaly. What beginners frequently play and what masters frequently play, are not the same. Any databases that you'll find are recorded from high level games, so won't match up with your games.

Why is the Sicilian not played as much? Well, the move 1...c5 makes a lot of sense from a basics point of view. To compare it to 1....e5 for example, both moves have the same primary goal, which is to control the central d4 square. 1...e5 also develops the Bishop and Queen though, whereas 1...c5 develops nothing. 1...c5 instead says that if White ever plays d4, Black can trade it off and still have both of his central pawns on the board.

Which explanation is simpler? "Control the centre and develop pieces" Or "control the centre in a subtle and none symmetrical way, whilst developing nothing"? Which move makes more intuitive sense to a beginner? Which move is more likely to be promoted by a parent or coach?

All the above answers are the same: the opening that develops pieces and controls the centre in a straightforward, intuitive and easy to grasp manner, 1...e5. Black will usually have his pieces out faster. He'll(/she'll) usually castle faster.

It doesn't matter at all, which move might have more "opening theory" for a master to know, should he play the move. That is not a factor. NOT AT ALL.

In summary, I believe there are two main factors for why you don't face the Sicilian much:

- There are simpler to understand/more intuitive moves that a beginner might play instead. It's not like your opponents are reading up on opening theory, after all. They're playing what makes sense to them, or what they've been taught to do, which is the second point.

- Some people believe that beginners develop faster from playing mostly 1.e5 e5 games, than they would from anything else. Is that actually true? I have no idea. It might be. It might not be. Some people believe it though, and that will contribute to what moves your opponents play.