A mortgage is about the ability to pay back hundreds of thousands over an extremely long time period. Your normal shopping is a blip, and it makes barely any difference because normal people just use their credit card the same as if it was a debit one (the only difference you pay it off at the end of the month). So it doesn't tell me anything about your ability to handle real credit. What do I care that you pay off a 100-ish bucks a month by buying food? I don't think paying off your shopping cart is very impressive, and someone telling me "I've paid off my shopping carts for over 15 years" (which is what advice US people seem to throw around to use your credit card for) isn't going to impress me, yet this is what a company uses for important stuff? And at least employment status/income tells me something, rather than nothing.