Why do some adults expect free when they invited guest?

So I have a family member that was invited out for a coffee outing from an acquaintance. But how they did it boggles my mind that adults can act like this.
After the initial invite to hang out was asked, they then explain that they don’t have any money for the coffee outing, yet they invited a guest.

I don’t understand why some people will invite others out, but expect something free out of the situation. And both people in this situation are well above 35 years of age.
Why do some adults expect free when they invited guest?
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