No it's not.
Charities have to report how much money they spend on things like overhead, and sites like Charity Navigator can be used to quickly and easily locate this information.
Your ignorance of it does not make it so.
Reporting many expenses as either "Programs" vs. "Overhead" is subjective; guess which way most charities lean?
I know this because I've been building a product for one of the most knowledgeable charitable tax lawyers in this space over the last five years, and have gone over many charity tax returns in that time (called T3010 forms in Canada).
Trying to evaluate the success and impact of a program is very important, for instance. But many charity's don't do it, because it adds "overhead" costs when you could be using that money to inflate a meaningless metric that looks good to donors who like to think of themselves as savvy.