If muslim banks don't charge interest then why do ours?

if i borrow $ 300,000 from western bank over 30yrs , i will pay back $900,000 approx. Arab banks have just a small set fee. muslim banks believe interest equals slavery, hmm , makes Sense. i am just a non religion truck driver from aus. i ask this question because the muslim are trying to do non interest loans in australia but the financial institutions here are fighting to stop them. is this because they approve of slavery ? evil maggots i reckon. not right. am i wrong to think like this ?