@jefito thanks for the link! Very informative. I assume business cards are read-only because they attempt to modify the phone's contact information, which is device-dependent. I just want to throw it out there that I, personally, would find the business card feature much more useful if it focused on working with Google Contacts and remained editable everywhere.
I scanned a few business cards using Evernote's business card scanner (in Android). Then I opened up those business card notes on my desktop, hoping to fine-tune some of the information in them. Instead I got an error: "Sorry, you can only edit the title of this note because it was created in another app." Why can't I edit business card entries from multiple devices? That defeats half the purpose!