Porsches are worth big money. The “costs” for hugs are more of a social calculation.

I expect that the act of taking a small social good that would not normally be available, or even allowed, but is being offered for free, feels subtly wrong.

“Why would this person give me X for free?” Makes us feel uncomfortable. We feel we are not seeing something, or perhaps freeloading. Which prompts a subconscious threat or status calculation, not a simple cost calculation.

But being able to pay for it suddenly fits a common pattern, even if the “product” (hug or conversation) is novel.