There is a special motive for VGchartz to don't show pc games selling?

Yes, we hate PC games. All PC games suck, and PC gamers are a bunch of unwashed, obese, cheeto-devouring basement virgins.

Or maybe it's just because PC games sell at a different set of retailers with very different sales patterns and tracking them is very challenging. One of the two.

If memory serves me correct, the biggest reason is because it is very hard to track PC sales. You can't track services like steam, or downloads straight from ebgames.com

Also, if the site was to only show retail sales (like walmart, bestbuy, target) then the games pages wouldn't reflect actual sales. And you would then have people coming in saying "game X sold 5m units but you only have it at 2m". However, those 3m may be from download only sources.

Where with console games, almost all of them are disc based only and are much easier to track. I mean sure some you can also download, like Burnout or GT5:P, but they are the vast minority.