If your group is too lazy to ask the server to split the tab 4 ways, what in the world makes you think they're all going to pull out their apps and pay this way? Then there's inevitably someone who doesn't have a smartphone, or doesn't have that app, or doesn't want to sign up for a new payment account, or doesn't like using credit cards online, or whatever.
More than a couple times I've been sitting there with people trying to add up their totals, some taking out cash, some taking out cards, arguing over who pays what, and just paid the whole thing and asked them to buy me coffee or a meal or whatever when they can.