A pool deck is assigned an occupant load. An occupant load triggers exiting. Some elements of exiting are dependent on the classification. Just because the pool deck is not listed in ch. 3 does not mean it is not an occupancy, it just means it is not one of the examples given. The pool and deck are structures by definition, and per 302.1 they SHALL be assigned a classification. If in doubt or the use is not listed, we are directed to choose one that is most like the descriptions given, as they can't possibly list them all. I don't think we can say it has no classification. The ambiguity comes from it's exclusion in any of the uses given as examples, and the fact that some aspects of it are listed in different A groups.
The occupants of the clubhouse are not required to exit through the patio since they have two other compliant exits. But the patio, which is enclosed by the clubhouse walls and pool barrier & architectural details such privacy walls and planters is required to exit through both the clubhouse and the pool. The pool has two exit gates, which are treated the same as doors. Doors would be required to provide panic hardware for an A occupancy. But which A? Does it matter? Probably not, but I like to be as precise as possible, and since the code requires a classification, is it enough just to say it is an A occupancy, without a group? OR, as the only other possible classification in my opinion, would it be considered a group U as a miscellaneous use? I think and have always considered it to be an A-5, just curious as to what others do. The difference between those two classification has an impact on required hardware.
CDA to answer your question: IMHO every structure must have a classification. A dog park would be a U. The fenced school playground is murkier, probably an E, since it is a space, and is an assembly space associated with an E occupancy. (I have never been involved with a school playground so I am interested in the strategy of others who have.) Assigning an occupant load to either space is up to the CBO. The panic hardware to get out of the pool area would be within the 34" to 48".