Since close to 10 years the suggestion to add the AED category has been proposed over and over all to no avail.
So I concluded that Google decided against doing so. I speculate that the lawyers put their influence on the line. Imagine if someone wanted to save a life and used Google Maps to find the nearest heart starter, and there was no AED to be found… And then they sue Google for incorrectly information!
In my country there is a fully maintained and dedicated AED map. To be on that map the individual AEDs must be checked yearly.