I think the other opposition to donating money, at least from folks in the US, is the same opposition to giving money in the form of local, safety-net aid. Everyone has seen the “people on food stamps shouldn’t be eating X!” Somehow, eating something fancy is a misuse of funds. People are afraid of getting conned into supporting someone getting something they don’t “deserve.”
Donating things gives a kind of moral control to the donor. If you send someone a $20, they might use it for *gasp* alcohol! or beer! or abortions! or avocado toast! or a fez, because who doesn’t love a fez??? No way. They only get to use the money in a way that supports 1. the sense of self of the giver and 2. the moral/social belief structure of the giver.
I know when Katrina hit, there was a whole lot of crap donations. One that I think made the news was an icky, old Santa suit. Because when a house is 1/2 submerged in water, that will help.
I prefer giving money. I can check out the fiscal ratings of a charity, and then the people who actually know what is needed can get what they need. And you know what, if what they need is a “luxury” that’s fine with me.