There are several reasons this is not a wise choice to be mandated to daycare providers:

• It will increase the costs, which inevitably will be passed down to families, increasing and already very high monthly expense for families
• You're expecting non-medical people with very little training to handle medication. They will have to get training, which is time and expense for them
• This is a potential solution for an extremely small number of children, and the expectation is that families with kids that have allergies take the appropriate precautions as a family. This mandate would put undue burden on care facilities.