We don't, unless they take a large enough mount that someone notices anyways. To me, that's more an argument that there should be more regulation here (Glass-Steagall was mentioned in another comment, which doesn't directly address this specific issue but it helps address perverse incentives in general) than the idea that people should have to spend time on this. Given how vital banks are to modern life and the number of purchases that an average household would need to check against each month, this seems like a case where the common good is better served by holistic changes than telling people "just do the work yourself". I'm politically more on the left than the average person though, so obviously opinions here will differ.