Sounds like an entitled teenager who needs some basic life facts explaining to them.
Children and teens often think they don’t need to thank people who provide a paid-for service, missing the point that basic manners cost nothing and don’t have to be earned anyway.
I’m always interested to watch small children and their parents. So many small children don’t show good manners and say please and thank you and their parents don’t pick them up on it. It’s absolutely not second nature to most children.
My view is that small children need reminding constantly and eventually it does become second nature to them. That’s the point when you can stop reminding them. Yes it’s a bit tedious but it’s worth it.
All people providing a direct service to us need thanking. Those earning low wages particularly need our thanks and it’s often those who people don’t thank are somehow see them as ‘beneath’ them, but the lack of thanking always reflects poorly on the silent person, not the worker.
I aim to thank all cashiers in shops, bus drivers, cleaners emptying bins where I’m working at work, people serving in cafes and restaurants, those seeeping roads where I’m passing by. I always wave thanks to those stopping their cars at crossings and drivers who pull over and give way to me. I thank those who stand aside to let me pass on a narrow path or during Covid.
Those who don’t thank usually lack social confidence or awareness in my view. Thinking your thanks is some kind of valuable commodity which is in limited supply and should be handed out sparingly is a reflection of a lack of social awareness and ignorance rather than superiority to the person they choose not to thank.