If I go out somewhere with a bunch of friends, we just ask for separate checks.
- the restaurant doesn't do separate checks for large groups - friends ordered meals with significant variance in case, and the server wasn't initially told to keep items separated - you want to split communal items in an arbitrary fashion
But anyway, some restaurants don't split checks and most don't like to because it's extra work for their staff.
Paypal fails like I said because of network effects. More people in my friend group have venmo than paypal (even though paypal owns both), so when it's time to pay, venmo is the default.
Nothing is inherently wrong with paypal, it's just that nobody in my group uses it. So, just plain old network effects.
When Apple Pay Cash came out, I was sure that it would replace Venmo, but even after all my friends updated to iOS 11 they continued to use Venmo. I’m guessing this has something to do with Apple Pay Cash not having any way to keep track of pending payments and requests, meaning your friend will probably never pay you back for lunch if the request isn’t paid as soon as it’s sent, before getting buried in history by conversation (iOS-only is another network-effect factor, but my social group is pretty much exclusively iOS).