Most business transactions involve the delivery of some good/service. You will generally know whether you've been scammed or not.
With aid agencies and donations you're often entirely reliant on their word as to whether your donation has actually made it to the cause they claim to support. If they're going to be using deceptive imagery, what else could they be deceptive about?
It is entirely possible to audit aid agencies in a reasonable way. There are entire organizations which do that, for example https://www.givewell.org/
Good luck finding that level of easily available transparency when trying to understand whether your next washing machine will more likely live for 5 or 15 years.