[stcroixx]

If you pay someone else’s debt without their consent it absolutely involves them. Of course the restaurant doesn’t care who pays.

[sneak]

How could it possibly? They aren't a party to the transaction.

[matheusmoreira]

They are. Picking up someone's tab is analogous to extending them credit. There are people out there who hate being indebted to anyone.

[sneak]

No, credit happens only by mutual consent. Paying someone's bill does not obligate them to reimburse you; extending them credit does.

[matheusmoreira]

It's still analogous to credit. Many people will feel like they owe you if you do it.