EPUB does feature digital Rights Management but not as requisite and efficient. That is the reason why it is used in Official documents across Banks, Educational Institutions and even the Government.
However, eBooks in PDF format has declined after the invent of EPUB. The digital copies of many books were released in PDF format. It was developed by Adobe in the 1990’s and it still widely used in official paperwork. One of the first and most popular formats for any digital document was PDF which stands for Portable Document Format.