That was my first question as well. Compared to a lot of other consumer electronics, designing fully wireless earbuds that are easily recyclable would seem to be an interesting (and likely difficult) engineering challenge. Both in terms of the physical design as well as surviving even a rudimentary cost-benefit analysis. Going by the AirPods and Apple Pencil, it seems like glue is the cheap, easy go-to solution when the internal components aren't enough to justify a major recycling effort. Though the case itself might be worth recycling. I'd think that the glue also helps with a better seal as well, but it's not like these are water resistant in the first place.
Manual recycling looks like a total no-go for these. They could probably automate some of the breakdown (ugh), but again, the recoverable materials per item are so low it couldn't be justified economically. Unless Apple ate the costs as part of their marketing efforts, it looks like the AirPods themselves go straight to the landfill.