Most often people don't settle because they feel reluctant to reach out and ask
"what is your zelle id?", "Do you have venmo linked with Splitwise?" , "How can I pay you?"

I suggest splitwise add a feature where everyone can mention on their profile how anyone can transfer them money. Which if you owe someone money you can look at the profile and pay them.

You can also add a "verified symbol" next to venmo payment to show the venmo account is linked to Splitwise and using the same email as Splitwise.