I'd argue they hide their takeaway because of what GP comment said — not because of anything innate, but because a staff member will not let them.

I grew up in an Asian household of six. We definitely took food home at AYCE places. My parents definitely knew it wasn't OK, but they felt like they were gaming the system (like a dubious life hack of sorts) and saving money, so they were actually quite proud of it, bragging to friends how much they were able to get.

To be human indeed!