My GT in US is tinted dark enough that you can not see into the trunk...
If I find a cargo cover at discounted price, I might buy one. Although so often these cargo covers get left in the garage when people fold down rear seats for hauling.
I like the fact that the Mazda one pulls up and out of the way with the hatch when you open it. Unlike some that attach just to the back side of the cargo area and you have to retract to load/unload easily. So now that I have it I never really notice it but it does give just a bit more privacy when the car is loaded for a long trip or when popping from store to store shopping.
$148 on MazdaGear. Mazdagear seems to have some of the best prices in my (limited) research. Bought my cargo liner from them and got it really fast, too.
Yes, $148 for the cover, but an additional $45 for shipping to my zip code, so $193 total.
It's $165 with free shipping at Med Center Mazda