It seemed like the person you're responding to was asking a rhetorical question that responded to the original statement ("here's your chance to put your money where your mouth is"), not directing a question at Mozilla itself.

As a response to that prompt, it's a completely legitimate question to ask: would my money actually be going where I want it to go?

Anyway, I think people do ask themselves where the money they spend goes. They do that all the time. It's the basis boycotting different businesses. They don't ask it in every case, such as when the question has been answered already, or where there isn't ongoing controversy about how money is being spent.