That's not true, one side is forcing the other side to live according to their believe system, the other isn't. Two examples:
1. Same sex marriage: One side: "nobody should be able to marry the same sex", i.e. I forbid you from marrying your gay partner. The other side, "everyone should be able to marry no matter what the sex", i.e. you are free to marry only other sex partners, as long as I can marry a partner of any sex.
One side is forcing the other side to adhere to their belief system, the other isn't.
2. Eating Pork. One side: "We believe eating pork is dirty, so selling pork meat should be illegal" the other side "Everyone should be able to eat the meat they want"
I suppose the problem is that in the abortion debate the pro life side believes the unborn fetus is being forced to live (or rather not live) according to another belief system. It's a matter of perspective I guess.
1. Same sex marriage: One side: "nobody should be able to marry the same sex", i.e. I forbid you from marrying your gay partner. The other side, "everyone should be able to marry no matter what the sex", i.e. you are free to marry only other sex partners, as long as I can marry a partner of any sex. One side is forcing the other side to adhere to their belief system, the other isn't.
2. Eating Pork. One side: "We believe eating pork is dirty, so selling pork meat should be illegal" the other side "Everyone should be able to eat the meat they want"