Why do people try to force labor??

Cristina • 2 years of trying to conceive. 2 Angel babies. Welcomed baby boy 06/01/15.
I've read a few posts about women trying to start labor early, some as early as 36 weeks. I also have 4 coworkers pregnant as well that are trying all these tricks to start labor. I just don't get it. Why not wait til baby is ready? I'm 37 weeks and sure I'm huge and exhausted but I want to make sure baby is healthy and ready to come on his time. I've read and heard of people eating pineapple, walking, eating spicy foods, asking the doctor to scrape their membranes (whatever that means) and all this other crazy stuff. One coworker told me she is desperate and will try anything to get baby out, she's also 37 weeks. I guess I just don't understand why.....I feel baby should stay in until he's ready unless medically necessary. What's with the obsession to evict baby????