Impression and public opinion is what they seem to be after, rather than proving that she actually did anything.
And why would that be?
It's all about Amy and Dave's main source of income.
No stunt running and "Impression and public opinion" means no way to gain attention for their charity and get sponsors.
No way to gain attention for their charity means no donations.
No charity donations means no hefty "administrative costs" to be taken out (and holidays in Spain lol).
Perhaps Amy and Dave will open the books for scrutiny.
And as mentioned elsewhere, Amy is just a tiny, tiny bit narcissistic.