Gosh. What a negative way of looking at things.
Of course the majority of boys will not get a scholarship of any description. They are after all supposed to reward exceptional talent/ability.
However.
My 2 DS both have academic scholarships, one at 20%, and nothing else is required other than a scholars' breakfast once a term - and putting in effort in lessons, which they'd do anyway.
I understand that scholarship amounts may have been reduced recently, but even so, Whitgift Foundation scholarships are generally know for being far more generous than most schools. I know plenty of boys with 30%+ for music or sport or academics.
And tbh if the school gives you a chunky scholarship, then why wouldn't you expect to give them something in return, be it performing for the school or playing matches?
If your son is required to sing at Croydon Minster, then presumably they are a choral scholar and as such enjoy singing, so where is the hardship for the child? DS1 only took up singing at T, so no scholarship, but really enjoyed singing at the Minster, as well as at more glamorous locations! If you CBA to drop him off at school for these - then give back the scholarship.
Presumably if you are awarded a sports scholarship, then you'd already be ferrying your DC to matches and practices all the time anyway. But if you don't want the commitment - give back the scholarship.
Are there many honorary scholarships at W & T? I am only aware of a few non-fee-reduction awards for music - but the child gets free music lessons, so that's a saving of £295 a term, it's not just honorary.
Finally, even a 5% reduction is more than £1,000 off the annual fees, which is not to be sniffed at imho.