Why do housing lenders charge more interest up front?

Why do housing lenders charge more interest up front? More interest is charged up front because the outstanding balance of the loan is higher. As time passes and the loan starts getting paid down, the amount of interest that is paid to the lender also goes down. If you look at a mortgage statement it appears the first few years are all mainly interest because the loan is much higher. The more time you spend paying your home loan, less money will go to interest.