This is entirely logical

Traditionally we here in Britain have not had a wildly intrusive government. It’s one of the things which keeps alive that flame in some that a wildly intrusive government might be useful or effective - a lack of lived experience of what actually happens with one.

Downing Street’s scientific advisers feared people might intentionally seek to contract coronavirus and that a black market in fake test results could emerge if employers allowed workers to return only when they had a positive antibody test.

The Scientific Advisory Group for Emergencies, known as Sage, was warned last month by its behavioural psychology subgroup that the widespread introduction of antibody tests could lead to a range of potentially dangerous and even criminal “negative behavioural responses” if not handled well.

How it is handled is less important than they might think. For we will absolutely, without any doubt at all, guarantee that if a chitty is necessary to earn a living then there will be a black market in the tests that lead to issuance of that permission. Plus a black market in those working without one, forgery of the pieces of paper themselves and so on. Along with all the associated corruption of the body politic that accompanies such systems.

We say this not because we are particularly gloomy about human nature, nor even because we want to laud some natural instinct to be free of pettifogging regulation. The insistence comes from simple observation of what people do in the face of such incentives. Among us we’ve experience of living in a number of different countries under different legal systems. Britain is, in daily life, remarkably uncorrupt and law abiding by the standards of the world around us. Largely because we’ve so rarely had a system in which it pays to be corrupt.

In any system where “Your papers please” is an important interaction in life then there will be a black market in those papers. This is not a prediction it is a fact.