Marriott partners with UNICEF in the Caribbean, Latin America, Europe, Middle East, Africa and Asia-Pacific in a program where hotels can add donations to guest folios on an opt-out basis. Generally $1 is added per night automatically, but guests can tell the front desk to remove the charge.
Autopilot opt out is the opposite of thoughtful philanthropy, so I was sympathetic to a reader who complained about feeling shamed by hotels that do this.