IRS Puts Open Source Projects Under Microscope, Spawns Nonprofit Black Hole (Wired)

Here in the UK, there are rules about the benefit that a
company is allowed to get in return for a donation. If the
benefit is more than (typically) 5% of the value of the
payment, then it is not considered a donation by the tax
authorities; rather, it's a payment for good & services.

But actually, your example is off-target as companies can
count both donations and payments for services as business
expenses. The important issue arises when it's not a company
(the hiking lodge in your example) but an individual who is
making the donation. If I, as an individual hiker, make
a payment to a trail maintenance organisation, then should
that be tax exempt? We might all agree that maintaining
hiking trails is a "public good" and deserves charitable
status, but there are difficult edge cases especially where
the thing being maintained is of benefit primarily to more
wealthy individuals. A good example here is private schools,
most of which still controversially enjoy charitable status.
In comparison to, for example, a charity that supplies
mosquito nets to Africa, it's far from clear to me that a
body that improves the software that I use in my for-profit
business should be charitable.