that is not possible. You can only select one table at one time.
The select command is restricted like you experience it in the graphical user interface.
But by scripting—as you are showing—you can address all the tables in the document and store them into an array to work on them one by one later in the code. Btw. stories.everyItem().tables.everyItem() does not address all potential tables in your document. It will leave out tables in footnotes and tables in table cells.
What do you want to do with the tables after you found them?
This is a question for the InDesign Scripting Forum over here InDesign Scripting
A moderator should move the thread.
1. I need to remove the ruler for all the tables, just top and bottom ruler should be there.
2. For first row, should apply THEAD paragraph style to the text, rest of the rows, TBODY style should be applied
3. In cell option, row height should be "At Least" and "11pt"
Moved to scripting per request.