@Maggie-and-Norm0
I don't know how much of it they will end up paying out for it to be honest.
The payments are broken down into three stages: creative, design development, construction. The winners have to complete each stage satisfactorily to get those payments, not just come up with a crazy idea. There are probably all sorts of hurdles in terms of local government planning permissions, labour and materials shortages (nightmare where I live with that that stuff since COVID, Brexit and the war in Ukraine), plus any other costs have to be covered by the applicant. In London, $100 doesn't actually go that far.
Basically, it's more of a PR stunt than anything else.