http://www.kalzumeus.com/2015/01/28/design-and-implementation-of-csvexcel-upload-for-saas/#oss

Specifically: "My company is literally not allowed by the tax code to donate money, but it can buy any software it feels like"

This might be true for 'patio11, but is this the case for many companies (e.g. ones in the United States)? Even where it's not true, is there some other factor that would encourage businesses to purchase a license before donating to an OSS project?

I'd like to get other HNer's perspectives on these points.