You are mixing different issues - construction operatives (tradesmen skilled, semi-skilled or non-skilled) cannot be likened to construction professionals (white collar) in the same breath. But I assume from a 'skills crisis' you actually mean construction operatives. There are many reasons for this - lack of job security (also construction is highly seasonal), working conditions, boom and bust cycles, a need to move where the work is, low attraction remuneration compared to other industries. Also, major contractors are expected to pick up the training bill, with no central Govt spending or initiative?