It is impossible to prove that all illegal immigrants are a drain on the system and so their cost to society cannot be used as a justification for repatriation policies. Many illegal immigrants pay taxes in some way and actually contribute to the economy of a country. For instance, every time an illegal immigrant buys something, they pay the same amount of sales tax or VAT as any other person. Illegal immigrants do not always undercut the labour market. The illegal workforce is a necessary part of the economy because lawful residents do not want jobs such as casual labour, agricultural or domestic jobs. Illegal immigrants often provide vital services that would otherwise be too expensive or hard to find if regular workers were employed e.g. cleaning, childcare and manual labour. Goods would become too expensive to produce if, for example, parts of the agriculture industry had to employ lawful residents/migrants.