This database was built using data from BEFORE Google required active ad accounts to get good keyword data & before they started blending data together for similar terms. Even if you set up an AdWords account and spend significant sums of money with them, they may require you to run your ad campaign for 3 or 4 months straight before they will show reasonably precise data instead of exceptionally broad data ranges.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.