if your company really cared about the cause then they would just donate without asking the customers to foot the bill

meh, there’s a lot more nuance to this.

(all assuming the charity is legic)

The companies aren’t really saying “we want to donate this money”. They are just nudging people to donate a little bit, with the goal that if a lot of people donate a little, the charity will still have money in the end (and the company gets a tax break).

You need to understand, that almost all of the people nudged will not donate to a charity otherwise. And now they have the chance to donate a little bit without much effort.

In the end, good charities have more money for their work. And that’s always a good thing