>A charity may not tailor their activities toward one or more individuals or corporations. Furthermore, while corporations can make donations, they cannot dictate how their donations are to be used.
Is this one of those things that's radically different in the US, or have I got the wrong end of the stick? Are there specific rules I'm not aware of for corporate rather than personal donations?
In the UK, it is the norm for charities to provide work-for-hire, like any other business, in order to fund its charitable activities. In general, this work is likely to correspond with the charity's mission, but it doesn't have to.
For example, the organisation I work for bids alongside private for-profit enterprises for local government contracts related to our mission - ie. we are paid by city or county councils to provide specific services - but in addition to that we also provide training services to other organisations on a range of topics, many of which are unrelated to our mission. In the first case, funding is provided which must of course be spent on providing the service in question; in the latter case, the income we receive is one of our limited sources of general-purpose (ie. 'core') funding that can be spent on anything (within reason, obviously).
This leads to the second part, about donations specifically: many donations, perhaps even most, are provided on the basis that they are to be used for a specific purpose. This is known as 'restricted funding', and is a pain in the arse. I'll make up an example, pretending that you're an organisation that deals with animals (not an especially *good* example, because everyone loves animals so you're relatively likely to have plenty of funding compared to other charities, but it's a simple example that shouldn't cause any offense).
Say you deal mostly with cats and dogs, and one year there are a number of highly publicised cases of feline abuse in your region. You end up getting a number of large legacy donations, to be spent on rescuing cats - enough to employ several people for a year. In the mean time, you have a dog specialist who you can't afford to pay this year.
For one thing, you're going to be looking at all of your activities with a view to determining which ones can be legitimately described as furthering the cause of cat rescue, so you can use your restricted funding for that, and hopefully free up some unrestricted funds. Obviously you're going to be performing full cost recovery so you can charge the relevant proportion of your administration, IT, rent, etc to your cat project.
At the end of the day though, what happens if you just have more money than you need to spend on cats, while there are dogs crying in the streets? For the future you need to be looking at fundraising campaigns targetted at the areas you can't currently afford, though you risk having the pendulum swing the other way. If you can't manage to accumulate a sizeable float of core funding you may find yourself hiring and firing based on what you have funding for right now. If you keep consistently getting more donations each year that must be spent on cats than on any other animals, you might find yourself slowly becoming a cat rescue organisation.
It's possible (I haven't checked) that corporate donations in particular actually can't be restricted (though I've never heard of that) in which case the article is technically correct ('while corporations can make donations, they cannot dictate how their donations are to be used') - or perhaps that's a regional difference.
The point though is that donations can very well control the direction of a charity, and in fact an organisation relying on donations is probably *more* likely to be susceptible to external steering than one that isn't. I guess this is the 'fine line' Sebro mentions; if so, I'd contend that the line is so fine as to be effectively nonexistant.
 Probably not most in terms of *number* of donations, but quite possibly most in *total value* of donations.