Public domain?

I'm currently reading "Fundamentals of database systems" by Elmasri & Navathe as part of the curriculum in a database course at my University. The book overall isn't all that bad, but their take on open source databases is really horrid. Quote:

"Personal computers and database system-like software products such as Excel, Visual FoxPro, Access (Microsoft), or SQL Anywhere (Sybase), and public domain products such as MySQL and PostgreSQL are being heavily utilized by users who previously belonged to the category of casual and occasional database users."

Wow. Public domain? I think they should at least invest two minutes to read up about open source software and open source licences, before they wrote about it. Excel and PostgreSQL in the same sentence? That's pretty fucked up if you ask me. And they have this highly patronizing tone which goes something like "commercial dbms > *, lol!". Someone should ship the authors a copy of PostgreSQL, I'm sure they would've been amazed if they tried it.