Well grids aren't essentially tables. I'm surprised by the comparisons here, it seems like many people have worked with either tables or grids, but not both. I frequently use both grids and table layouts along-side each other.

Tables are especially helpful for creating a horizontal list of elements that are evenly spaced, but of uneven/unknown width. You can't do that with a grid. Since grids are floated, it's easy to adjust the number of elements in a row (by either changing the width or the row or the width of the items). You can't do that with a table, since each row has to be delineated in the markup.

I don't use table elements for layout of course, I use display:table. Using a table element for non-tabular data would be unsemantic, unlike using a div which carries no semantics.