It's to prevent I claim they're mine. And I do not.
You have limited rights to personally view the images with your web browser and to use them as your personal computer wallpaper (or background image) on your own computer. These photos may not otherwise be reproduced, distributed, cropped, resized, or otherwise altered without the written permission of the photographer.
Its says on the website that they can fly only to the countries where there are no noise level restrictions (and probably no safety regulations too )
Ever thought taking a boat instead?)
That is just one reason. I'd suggest reading the a.net usage policy. Another reason is that by distributing the photos outside a.net, you are effectively reducing traffic (pageviews) to the site, which is one of its only sources of income.
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