"I'll tip you good" I just want to say, I doubt it

Had an elderly couple just today, “this is our 2nd time using lyft, we gave a cash tip yesterday but then realized afterwards we can tip on the phone, is that right?” Me, yep! Granny “ok well we will just do that then.” As we pull in to their hotel, they wait asking me to end it before she steps out so she can make sure and put the tip on. Still no tip. Thankfully the next guy, who never mentioned tipping, gave me $5