Ah, it's a terminology problem. The table background is transparent, but the borders are not. (Sorry, used to thinking about tables from a CSS point of view). It can be done, but would require a Stylus style that would affect all tables, and only for the machine on which it was installed. There are some scripts (like Stephen S's Markdown) which give you full CSS control over handout display, but that would require a Pro account. *I had considered the text editor replacement, but the engine itself was replaced way more than three years ago, IIRC.