I accept it is totally subjective. If a 35 year old woman looked like a teenager (rare but can happen) then yes she might be referred to as a young woman. If i was mugged by a woman in her thirties I think it would confuse the police if I described her as a young woman!
If I was told at work that a young woman was joining my team, I would expect a school leaver not a thirty odd year old woman. A thirty year old is just a woman - not young, not old, not Middle Aged.
i have never heard anyone refer to a theory year old man as a young lad, a young man etc. Just a bloke or a man.