> If the EU is a mutal-defense agreement why are all these EU members trying to also join NATO?
Because mutual defense agreements and other joint security agreements aren’t mutually exclusive, and NATO has an integrated military command and more nuclear powers as members.
I don't think Finland has high confidence that the binding agreement will save them.
If you look at the polling for if Finland should join Nato there is a huge spike after 2022 [1]. Even Sweden which has a buffer between it and Russia also had a increase in polls [2]. Not that anybody does this poll, but you won't see a spike in if say Canada should join the EU. The point being, these countries do not trust that the EU will protect them.
Such agreements only force-project the illusion of a larger, unified entity as opposition to anybody who might act against them. It is a deterrent at best.
It has yet to be witnessed what hilarity ensues when any of them simply refuse to answer the call.