Why is 70-300 VR so cheap?

KG2002 wrote:

I am looking for a travel zoom lens for D800. I use 50 1.4 and 85 1.4 70% of the time when travel, 17-35 2.8 15% (for landscapes) but need a decent zoom to cover the long range. I was looking at 70-200 VR II 2.8 and the new f/4, but they are still too big for my bag and honestly, for my purposes 300 would be much better. I would even prefer a super zoom but the quality is totally off from what I read. Distortion, bad sharpness and etc.

I know 70-300 VR is not a pro lens, but I do not need it for stock or anything. Just good quality photos for myself. I read reviews and it looks to me as an average lens which is fine by me. Much better than 24-120 actually. Also comparable to 80-400 from what I read. However it is soooo cheap comparing to the rest of them so it makes me wonder what I am missing? How can it sell for $450 while 80-400 is 3 times more. Yes, build quality and so on, but the test results are very close. How can it be?

I have very little experience with zooms - I only had 18-200 for my wife DX camera. It was super convenient when we travel. The pictures were ok but the difference was quite visible even if I scroll through the album quickly.

Any word of advice?

P.S. I am not going Tamron or Sigma way with zooms. I had one very good sigma prime, but heard bad stories about Sigma zoom quality.