I lied to a customer in a shop about an item in stock and I didn't care and neither did my manager
Why did you lie about it?
I don't know, it was just easier than to have that interaction.
Telling lies to customers is bad for business. Customers will stop shopping there, and soon you might be out of a job.
My job is pretty useless. I didn't care about the customer or my job, so It's fine.
If you show up to work you are expected to tell people the truth and do your job. Avoiding people might only make more questions for them to ask you. And if they get angry they might cause a scene.