Tipping is hardly done from one's free will volition and has graduated into an informal bribery.
Giving excuses is one way to indirectly ask for tips (bribery). It's rather unfortunate that such gateman and like many others have viewed tipping as an entitlement.

Favour is often tied to tips, a kind of rub my back while I rub yours.

Many of the people involved are uniformed or security officers, perhaps a form of oppression unless a financial commitment is made.