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> Having different CCs is harder than just multiple emails.

Don't many banks issue virtual debit cards at negligible or even at no cost?

Even with virtual debit cards, this kind of data is still extremely useful from a fraud prevention point of view. Maybe you can spot a pattern that signups on one particular brand of virtual debit card from one particular IP range are most likely to be abusive. With fraud prevention, anything additional that can be used as a signal is useful.

They do but don't they have the same address & name ? At least it confirms identity.

I'm not sure a typical bank card detail form include an address. Usually it's card number, expiry date, CVV/CSC and (optional, as some cards don't have it!) cardholder's name. Not sure about Heroku and too lazy to remember a password and log in there to check right now.

Heroku may have address fields for invoices and stuff, but I really doubt they can validate it (except for country/state) with bank, as addresses are real mess. At the very least, not automatically. So, this probably won't work for abuse prevention.

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