Panda, in a since I agree with you. It is reasonable to have a specific amount of CPR certified people always in the building. On the whole, the chances of a child needing CPR are small.
However, I don't feel it is unreasonable to expect that my childs teacher is capable of responding in a crisis situation and not having to run all over the school to find someone that can. IF, and a big if there, something were to happen, the few minutes that it takes the other person to respond could make a big difference.
When I interviewed people for the responsibility of watching over my children while I was at work, one of the first questions I asked was if they were certified. Why should I expect less of the teachers that spend all day with my kids than I do of the woman that spends approximately 6-8 hours a week with them?