Why may cost-plus sale (مرابحة), leasing (إجارة), advance-purchase sale (سَلَم) and Istisna‘ be used in Islamic finance?

They may be used in areas where partnership (مشاركة) or investment partnership (مضاربة) is not workable or feasible
They are all different names for the same interest-bearing loan
They remove the need for contractual conditions
They are used only for charitable donations