The folks at universal symbol headquarters put in a bit of extra work on this sign knowing how important it is. They added colors that are recognized almost everywhere as "Yes" and "No" in the event that someone might mistake the meaning of the symbol resulting in an unfortunate event for the person using the facility or the next person who enters. I encountered this sign at Arches National Park and initially questioned its need. Then I remembered how many citizens of other countries visit our national parks each year and that millions of people use slit trenches and not toilets.
To the employees of the U. S. Park Service, I say "Thank you" for making these signs large and for posting them in conspicuous locations at your facilities.