Why relativity allows quantum tunnelling to 'take no time'?

In quantum tunnelling, what appears an infinitely fast barrier traversal can be explained in terms of an Aharonov-like weak measurement of the tunnelling time, in which the role of the pointer is played by the particle's own coordinate. A relativistic wavepacket is shown to be reshaped through a series of subluminal shifts which together produce an anomalous 'superluminal' result.