Identify whether the following is illegal discrimination and briefly explain your reasoning. Providing just yes and no answers are not enough for credit.

A restaurant refuses to serve anyone who is Swiss.

A restaurant refuses to serve someone who arrives for dinner 2 minutes before the kitchen closes.

A restaurant refuses to serve someone in a wheelchair with a service dog because the restaurant doesn't allow animals in the dining area.

A hotel refuses to provide a hotel room to a couple because they are not married.