I think it's a matter of semantics.
The morning-after pill is an elevated dose of hormones. It does one of three things - prevents ovulation if it hasn't occurred, prevent fertilization if ovulation has occurred, or prevent the implantation of a fertilized egg. If the morning-after pill is taken AFTER the zygote is implanted, it doesn't do anything to harm the pregnancy (as I understand it)
Since technically, a woman is not considered pregnant until the implantation occurs, and an abortion is ending a pregnancy, then the morning-after pill is not, in fact, an abortion pill.
Of course, if you believe that life begins at the moment of conception, then taking either pill could be taking a life.
There are plenty of medications that can cause the fertilized egg to not continue developing. Should those fall under the same rules proposed for birth control and morning-after pills? Because if they don't, I bet you'd start finding off-label prescribing of those medications.

What is the point of rules that are not enforced?