People left at different times and put cash on the table for their share on their way out. You never wanted to be among the last to leave because, inevitably, some people only left enough to cover their drinks but not enough for part of the tax and tip.
I am all for a single check IF everyone is going to pay their fair share. I'm even all for a single check if someone's share is minimally larger than mine. But if I get a salad and a water and my companion gets some chicken wings, a steak, a piece of cake and two glasses of wine? Not happening. Also, in this day and age where few of us carry cash anymore, how does splitting a check work? One person uses their card and everyone else Venmo's that person? I don't have anything like Venmo so unless all my dining companions also have cash like me, it's awkward not to get separate checks.