I hope they don't. Really they shouldn't be exposing the BIN of the actual card number at all, they should be exposing a token. Your payment card number shouldn't be used to make decisions about your credit worthiness or profile you.
The BIN/IIN is pretty useful for various reasons. For example, identifying that your customer has a Mondo (https://getmondo.co.uk) card and automatically pushing rich transaction data to their statement.
