Ok, humour me for a moment.
If the tennis club CCTV was secured quickly enough to get footage from the day WT disappeared, then there's a chance LE already knew about the 2 cars.
Let's say it's several weeks later (or March 2015 - whatever is correct) and LE hears of Chapman's detailed sighting of the cars.
There's a chance that:
1) What was on CCTV has been corroborated by Chapman's detailed info.
2) No cars appeared on the CCTV to corroborate Chapman's sighting.
Beacroft has said in the inquest that she believes Chapman is a trustworthy witness - read into that what you will. But the inquest hasn't mentioned tennis club CCTV. Either that's a strategic move, nothing appeared in the footage, or they got the footage too late...
Interesting to ponder!
Drip feeding comes to mind...a card face down on the table...I personally believe only limited info is being released publicly in the inquest, to progress the purpose of the inquest only and no more. It's so intriguing.
IMO