If these positions cannot be filled there will have to be wage increases which will result in higher food bills but may go to address the imbalance between low paid workers and those in white and blue collar jobs.
I totally agree with the highlighted part but I dont think what you say may happen will be the case. It think it is more likely that the working class will get poorer as a result.
It's all about supply an demand, generally speaking, if a particular job is in demand, the only way to fill it is to offer more money, better benefits and working conditions (i.e. offer a better package than your competitors).
It may be that less suitable people are employed to fill those positions and employers may not have the luxury of being able to pick and choose who they want.