No it doesn't. Because if you open one up, it consists of several pieces of glass arranged in several groups, held together by an optical tube assemble which can be made of metal or plastic. It also contains precision spacers to hold the groups of lenses apart precisely. Calling a "photographic lens" which is complex "a piece of glass" just shows an attitude problem.
same here. I think its just a photographer slang. Photography or otherwise, when one spends a long time in one field, one tends to gather a good collection of slang, and when/if a newbie (i am a one) starts using slang indiscriminately, the newbie generally ends up looking like a wannabe rather than like a seasoned veteran.
Blatant generalization, but there you are. I am *not* saying that slang must be exclusively reserved for veterans.