Because its 'reserved parking' between these hours
Mon - Wed
am - 7pm
thurs - sun (i think sun)
am - 4pm
meaning you can't park there as its only permit holders or reserved parking for those with permission. I presume the machines are probably turned off to prevent you from buying a ticket but thats what I was told
and I've just looked at the car park on google maps - its the car park on wandle road and is council, there is a sign and saying permit holders only and paid parking but if you look closely you can see the times below in small enough writing and you can see the cameras.
its the open car park not the multi level one.