Why don't we have such an emphasis on the Holodomor opposed to the Holocaust? ?

Agreed, but U.S. schools mostly focus on issues that relate to our history. Our troops were involved in freeing the Jews. We also have a large Jewish population so it serves the public interest to focus on specific incidents. By the way. There are many situations around the world related to the extermination of a people that aren't taught in schools. There is the genocide of Native Americans, African Slaves, etc. You can't really teach everything in schools because there is little time to get information into the students. This is where College is important.