This is really a matter of tradition, which varies by context. At the University of Chicago, only MD's are called doctor, by general consensus. Others are "Mr.," "Mrs." or "Ms," including the most distinguished faculty members. However, down the block a ways at the local high school, anyone with an Ed.D. is "Dr. so-and-so." In public education, an Ed.D. is treated as royalty. It's likely due to the differing values placed on different degrees. Or, at the U of C, they just assume you've got a Ph.D. :-)
This is really a matter of tradition, which varies by context. At the University of Chicago, only MD's are called doctor, by general consensus. Others are "Mr.," "Mrs." or "Ms," including the most distinguished faculty members. However, down the block a ways at the local high school, anyone with an Ed.D. is "Dr. so-and-so." In public education, an Ed.D. is treated as royalty. It's likely due to the differing values placed on different degrees. Or, at the U of C, they just assume you've got a Ph.D. :-)