  This paper investigates whether changes to late time physics can resolve the
`Hubble tension'. It is argued that many of the claims in the literature
favouring such solutions are caused by a misunderstanding of how distance
ladder measurements actually work and, in particular, by the inappropriate use
of a distance ladder H0 prior. A dynamics-free inverse distance ladder shows
that changes to late time physics are strongly constrained observationally and
cannot resolve the discrepancy between the SH0ES data and the base LCDM
cosmology inferred from Planck. We propose a statistically rigorous scheme to
replace the use of H0 priors
