Depends on the program. Competitive programs are competitive. There are plenty of programs that don’t fill every year and very few applicants who don’t match. Those that don’t match often don’t match because they were geographically limited and didn’t get into the 1-2 programs they applied to. I only know one person who didn’t match and that was because he applied to one program where his wife was doing an IM fellowship and then the Tox program lost funding for the fellowship spot for that year.
Also depends on the interest. In general, those that do fellowship in EM are probably looking for academic positions, particularly in tox, which is not a large proportion of people who go into EM overall. Cards/GI is generally going to be more competitive because more people are interested in pursuing the fellowship, partially due to the fact that you can make bank in private practice after the fellowship. So it’s not just limited to those who want to do academics. Tox is not the most lucrative in private practice, it turns out.