Ah I get it now. My question was like asking why mailto: links don't take SMTP servers into consideration. In the US, this is going to be used to print checks

Ah I get it now. My question was like asking why mailto: links don't take SMTP servers into consideration. In the US, this is going to be used to print checks ;) The ACH links will be opened by the check printing program to print the check and send it through the mail.