Dave Plowman wrote:

If you were to measure the speed of rotation of the wheel at any
single point on it that would vary depending on where it was to the
road contact point.

The ABS sensor will measure the speed multiple times (e.g. 48) per
revolution of the drive shaft, not just a single point.

Virtually no drive mechanism transmits a perfectly uniform speed
from input to output. There is invariably a degree of 'chatter'.

The TPMS operates over a longer period of time, probably minutes rather
than seconds, so over many revolutions of the wheel, likely the numbers
will get averaged out before it decides one wheel is turning faster than
the others enough to flag it up.