In the US, everything needed to initiate an ACH is printed on a Check... and people feel very safe writing checks to one another and to companies. You never really know who sees your checks, where they are stored long-term, etc. Also, it's trivial to find a website that will sell you a box of checks, they do no verification to your identity/ownership of the accounts, they basically just print what you tell them to. Nothing is secure about banking, it really does need a modern reboot where we just sever ties to the legacy features