I am comparing our local GS with private schools I know of.
Private school demands, for example, a particular style/colour of trouser from a specific shop; GS does not.
Blazer for private school is expensive (£100+) and needs dry cleaning - GS £30 washable with badge.
Private school demands lunches have to be taken; GS can choose.
Music fees are often 'topped up' at a private school by the need to pay for 'their' accompanist ...
Local private demands three/four (rugby, indoor, cricket, outdoor) different types of shoes for sport plus cricket whites. Those in teams need tracksuits plus own equipment which, for cricket, is not cheap. GS needs two shoes (football, trainer) and all other equipment is provided.
Private school seems to expect lots of art equipment to be bought - sketch books etc.
Many private school DO require textbooks to be bought plus folders etc.
Fund raising events - wel at the private school you need a mortgage to attend some of them
GCSEs/A levels are expensive - no cost in a state school.
Yamin151 - we've not ever been asked for any expensive 'extras' when DS was at GS.