Why can't you say 'the young live in hotels,' which is how most Americans would phrase something like this.
I think it's because ungdommen is referring to a single young person, rather than the collective youth.
That is not really the case, "ungdommen" does refer to the youth/the young people (therefore a group & not a single person) Take a look here, particularly definition 1.b :
I'm not sure but I think that that should be accepted as well. Try reporting it ;)
Youth lives is very poor English. "Young people live" or "youth live in hotels" is the correct statement.