I'm sure Christian can explain this better than me but my (poor) understanding is that:
* If you get a persistent object twice from the same EntityManager, then it takes care of returning the same object. Thus, the default equals and hashcode work.
* Equals and hashcode are *hard* to get right when using persistence (you need to use a natural id - not the pk) if you want Collections to work with detached objects.
Therefore, as Seam's LRCs mean you (rarely) need to work with detached objects, you neatly avoid the equals/hashcode problem.