Just because many people are in favour of a policy does not mean it is normatively justified. Policies that have little to no efficacy and actually even create the opposite outcome than is desired are certainly not justified by this logic. People only want a fence because they think that it will protect American jobs and border security. If a closer examination of the economics of illegal immigration demonstrates that immigration actually grows the economy, it seems nonsensical to continue maintaining the fence. This just perpetuates racist attitudes.