There is a version that passports of red color are used by communist countries. Although many countries have got beyond control of the former Soviet Union and Russia long ago, the color of passports has remained the same. Among them are China, Russia, Latvia, Poland, Georgia, Romania, Serbia and Slovenia.
Many EU countries (Northern Europe) have claret-colored or red passports. This happened historically, often since the Vikings and the Middle Ages times. Such countries include, for example, Germany, Switzerland, France, Norway and others.
There are some countries that have changed their color to red. Perhaps to accelerate the accession to the EU membership: Turkey, Macedonia, Albania.
Some countries of South America also have red passports: Ecuador, Peru, Colombia and Bolivia.