The answer actually is very simple. The only people who can drive down wages are the people who pay the wages. There are not many unskilled/temporary/seasonal workers, especially if they have come to find work to support their families overseas, who have the choice to say to an employer, stuff your low wages, I won't work for you, go and find a Brit instead. Blaming EU workers for driving down wages is xenophobic and was a mainstay of the racist brexit campaign. Just try to remember that we are talking about large numbers of people who are not organised to fight back and who the Tories have made sure enjoy no employment security. The Tories refer to them as the flexible labour market. Us lefties refer to them as vulnerable human beings. And where they come from is immaterial.