Emergency services in my city (the one you call via phone) have a "true emergency" rate of about 1 in 10 according to emergency personnel I talked to, so it is always a matter of balancing the false positive/false negative rate.
Seconds literally matter for many emergencies.
Your position makes the assumption that the rest of the emergency services infrastructure is at maximum use at all times.
The OP was talking about a place where they use volunteers, so it's not likely that they're constantly in use.
While you are correct that seconds can sometimes matter, it's not always true. Not every emergency call is life-or-death. Not every emergency call even requires a response.
Imaging a hypothetical world where every call is a true emergency, and emergency services are at 100% utilization 100% of the time is arguing just for the sake of arguing.
I live in a place where emergency services is over-taxed. But I'd rather have actual lives saved with a certain number of false alarms than have people die because someone decided that perfection is the only option.
That would be even better, as that would mean 3/4 of the alarms are hits/non false-positives. I argue that even a 1/4 hit rate, i.e. 3/4 false positive rate, is a good start.