Why is it that most manufactures of bows use Maple as a core or outer lams and Bamboo as well but rarely Hickory ,Ash and others. I use Maple exclusively because its readily available and quite inexpensive.  Have used some Hickory but found it to lack Elasticity compared to Maple.

I think you answered your own question. It's readily available, cheap, and consistent. For me the problem is, it looks blah... bamboo too, so I don't use them. There are plenty of others that work fine and are much nicer to look at. I guess I could use them if I put veneers over them.