As having contributed to many open database and as user of many open database, the CCZero is my default choice for making data open. Adoption of this license is, IMHO, the prime reason Wikidata is growing so fast, and integrated so fast in many use cases. License incompatibilities have been a major concern in open source development and academic research. Yes, there too, there is a continuous almost-religious and unsolved discussion about copylefting, but the plain experience there is that the closer to the idea of public domain, the easier it is to use. The advantages of CCZero have been widely discussed in the life sciences, and while not everyone choice, the benefits outweigh the disadvantages for many. I also note that public domain (which CCZero formalizes across jurisdictions) is still the "ideal" license when uploading images to Wikimedia, suggesting more of Wikimedia actually finds the CCZero idea very welcome.

Also stress that in no way I recognize myself in your comments about Denny and Google. And your comment that "freedom of one is murder and slavery of others" needs some refinement, IMHO; my definition of "freedom" is quite different and I experience your definition as abusive and offensive.

I hope this helps,

with kind regards,

Egon