Why is human trafficking so big in romania & ukraine? What is it about these 2 countries?

well im from a small country between uk and romania(Moldova) so i know that all these countries are very poor,economy may be good but the way people live is poor,and a lot of young generation is looking for a good future and where is the future if not in europe.thats why they very often are sold or used.of course they are told that they go to work as model but is not right.