Data validation rules do not extend while adding new rows in a table.
While formulas in columns extend with new rows added to a table, data validation rules do not. That's unintuitive and very inconvenient.
Andrey Minakov commented
Bryon, thanks for your comment. Yes, I refer to "plain" tables (Insert->Table of the Ribbon). Please could you say what do you mean under "Data" table? Data table of What-If Analysis?
Bryon Smedley commented
Data Validation works if the table has been "upgraded" to a Data Table. Are you referring to "plain" tables?