That is very simplistic. There are a lot of other recurring costs that charities have - even the ones you mentioned have to pay rent at least. A women's shelter probably needs professional employees. Some charities have to operate planes and boats and those are very expensive. The most important thing is - recurring contributions help them plan long term and realistically gauge if they can take on more projects.

Also, calling a monthly donation a "subscription" is stupid. You didn't sign a contract - you can just stop giving the money whenever you want.

No. The charity muggers in my country come around to my door, or meet me on the street, and they will not take a one-off donation. They want you to go for an ongoing monthly subscription of direct debit from my bank account or credit card that requires time and effort on my part to alter or cancel.

And while they are not the main problem, they are a symptom of the subscription epidemic. When I cannot simply give them 50 bucks because they do not have the means (or willingness) to process it, that is a definite sign that subscriptions have gone too far.