The value of shares in most private companies can't be assigned a dollar value (since you can't sell it easily), so that column is meaningless for a lot of rows, including most startups. Also it's important to remember cash salary is often discounted in favor of higher equity at startups.

I think a more relevant column to add would be percentage equity for startups/private companies (subject to vesting). And if you're at a private company and you don't know the percentage, you should ask.