Free Business Idea - Tap to Tip

I keep a list in Google Keep of all of my hair-brained business ideas. 90% hit me on a run/ride. When I look back a day/week/month later, it's comedy gold. I'm full of bad, unworkable ideas. Here's one I'm not qualified to execute on: TAP TO TIP. 

Nobody carries cash anymore, and service industry folks are getting the raw end of that. When I was in high school/college, parking cars at a nice steak house could make you hundreds of dollars in cash for hustling and being polite. That number is shrinking.

This is where Tap to Tip comes in: you put a small RFID badge on any employee eligible for gratuity, and anyone wishing to tip them can just tap their phone/watch. It's quick. It's convenient, and it gives management real visibility into their best/brightest.

Where else can it work? How about charities being able to give "buttons" to their volunteers? 

What say you?