I don't mind them not explaining stuff, I do hate it though that his sister doesn't even bother to ask where he got all that money from even though Kirito doesn't know shit about the game and doesn't even try to hide it

no matter how you look at it, for her it must seem like she is playing with a cheater/hacker and she doesn't even care
"as long as he is in my team, he can do whatever he wants"