If I sit down at a restaurant, and get served well, I'll leave a tip at the end when I pay. Hell, even if the service isn't great I'll still leave a bit of a tip.
But now there's this idea that you should tip for service... before you get served. The tip jars at Starbucks, apps that ask you to input your tip before you get your delivery, POS systems that ask for a tip, etc. There's no way I'll ever tip before service, and probably won't after either if the business is audacious enough to ask for a tip when they're using a pay-before business model.
I'm looking forward to seeing how long it takes for self-service gas pumps to start asking for tips. After all, there's an attendant inside keeping an eye on you, so that's a service right?
I'm sure these businesses have found that merely including the dialogue = free money, so why wouldn't they?