There's a big difference between it being handy to keep a bit of your gate in cash for some clubs, versus being clobbered for 17.5% of your gate revenue in tax for each and every game.
One involves choice - not all clubs do it, those that do will do it to varying extents at varying times, and I doubt many have the nerve or the stupidity to under-state their crowds by as much as 17.5% each and every week.
P.S. What 5,000 crowd ??