The fact that some of the other websites have song lessons or tabs that GT hasn't doesn't mean those websites have obtained the legal license to use them or that the tab is correct.

I think GT does it the correct way by obtaining the necessary licences and having the lessons checked over and you know it's correct and legal. I would much rather wait for a legal version of the song lesson than support other sites that are not doing things correctly.

Another note to consider is that certain songs may be already licenced to other sites which could then make it not possible for GT to obtain that licence.

When you consider how much an annual subscription to GT is and the fact they have a bigger library of songs and lessons than thier competitors even though there is a gap in the songs an individual may want you still get a lot for your money with GT.