The compelling thing for me still with checks is that the banks take on nearly all the costs of processing them, and what costs are imposed on the customer are fixed, and do not scale with the amount of money being transferred. It's possible to do fixed-cost transfers using other systems (PayPal, Venmo, etc.) but it always feels like those transfers are only tolerated, and they really want to push you to their other offerings where they can get their vig.