Why players are not accepting draw in %100 draw positions against a similar opponent

İn move 42 it was sure that it was a draw but my stubborn opponent played 22 more moves

Because it's not a draw until the game is over.

There are a few - apart from a scenario neither of players is an IM / GM knowing the position is a theoretical dead draw, but continues playing for some fun / the crowd / educational purposes:
1. There's always a chance that one side blunders.
2. There's always a chance that one side runs out of time.
3. There's always a chance that one side doesn't evaluate the position as a drawn one.
4. There's always a chance that one side is just stubborn.
5. Other..

BTW is anyone else eager to see a CAPTCHA like this:

White to checkmate in fifteen moves
This is a chess CAPTCHA.
Click on the board to make your move, and prove you are human.

I'm sure the forum would thrive.. :-D

If I have learned anything from chess it's that there is always plenty of time to blunder. The game isn't over until it's over.

Your opponent may also have been just as aware as you that the game was a draw but wanted to practice his endgame chops.

They're not GM who!
"It was in this position on, move ..... That both players agreed to a draw!

Because many players are disrespectful jerks.
The sad thing is that it sometimes works for them. They bore you to death with their endless tries to win the draw until you blunder in one moment of carelessness as a result of being so bored and fed up with that game.

Because he is about 200 elo higher then you and doesn't want to draw and lose some elo while there is still time for you to blunder :)

Mostly agree but your technique looked a little jittery, I don't really like your moves Rg8 and Rh8 as they may give your opponent the chance of invading with the king while your Rook is the wrong position. Also once you played f3 I can imagine Black dreaming of getting his king round to f2.