I don't think you understand what donation means.
It's not free money if the "donor" is getting something in return. Or maybe I'm wrong and I've been donating a lot of money to Amazon and all the things they send me are just "perks" I guess.
As someone who is in their second year of Creative Writing and has handled donations both on a Garry's Mod server and has raised money for facilities before in real life, I am actually cognizant with the definition of donation, thank you very much.
By free money I mean it's their money they choose to spend on recreational goods, and they are instead opting to use it to contribute to the project. We're not analysing their thought process and saying "Well he's only doing it for the benefits that a donator gains, so he's clearly not keen to help us out and is only in it for the rewards." Every donation is taken seriously and handled the same way; a user gives away their money which directly contributes to the running of the website, which results in us thanking them with giving them perks. By doing this, we appeal to both those who which to donate out of the good of their heart, and those who simply want the perks, and treat them both the same for their actions instead of assessing what a user's intentions are.
So figuratively for some users, it may not entirely be donating, but for others, it actually may be. We'd rather not alienate either party and hit a middle ground so we can obtain as many donations are possible.