I am not an expert but the difference between death penalty and abortion is that there must be a trial of the accused by a jury of their peers. 

How many babies would condemn an unborn child to death? The baby is obviously innocent and thus it could be called murder. However the woman and “doctors” who commit it could only be “punished” by an honorable accusation and a jury of their peers. 

The thing is we don’t have a proper legal system right now 

Jury trial isn’t being respected in its true form. 

https://mises.org/library/book/lets-abolish-government