I think it is normal and healthy to wonder why someone would not call back (only as a passing thought though). It helps us re-evaluate our services. However, I think that we could offer the best meals, crafts, environment and so forth as well as have a great loving personality but if the parents or the caregiver don't feel the connection (the click) it just won't happen.
Remember you could never please everyone.... and at the end of the day why would we want to? It is about our families, ourselves and our daycare kids and families.
It's not personal. I can't help to think that if the person does not have the respect to call back and inform you of their decision, you likely did not "click" with them as they do not share the same values, respect and manners.