Another key paragraph is this one:

“This gives Air Canada employees — and anyone else capable of accessing the screenshot database — to see unencrypted credit card and password information,” he told TechCrunch.

The takeaway is that some companies are capturing things that they shouldn't be storing, and the article has exposed atleast one instance where this information has been sent to a third party without masking.

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As a side note, I've always been afraid to use payment options within apps that redirect to bank logins or payment gateways and this only feeds my fears.

Even if you're making the payment through a trusted bank or a payment provider, these apps still probably intercept and store the information you gave your bank.