I think the difference is that in one case I am dealing with Walmart (or whoever) and I don't care what they make as long as I get the promised services in return for that money.

OTOH, on Patreon the messaging is that you are paying the creator, so I am kinda dealing with the creator with Patreon as the intermediary, and when it says I pledge $1, it feels like I am paying the creator $1 for their service.

I mean they should at least say how much the creator will receive, and how much he won't (patreon fees + credit card fees, I don't care about the details).

Once again, when you donate to an charity or buy a product from the shelf you don't know how much the charity or retailer would receive when you pay with a credit card.

Not unusual.

When you check out in Walmart how much is the fee Walmart pays? You have (basically) no idea.

Of course not, but it depends if you consider that you're paying the creator, and that the platform is just an intermediate, or if you're paying the platform for a service and they pay the creator with their revenue. If they're just an intermediate and I want to pledge 1$ to the creator, I expect that he will receive 1$, and if not, I want to know how much I need to give in order that he does.

And you're wrong about NGOs, usually they do provide how your money will be used, what is the amount of money that will go for their internal costs, and what will be used really for charity. I wouldn't absolutely not give to a charity that would not provide me those details.