Hi there,
If you look at the images again there is clear discolouration of the stickers. It is visibly more yellow than the plastic of the tapes themselves.
I bought these tapes from a collector 15 years ago, when I bought them they were all in individual boxes and I have stored them in the exact same boxes and in a dry environment at room temperature. There is no reason for excessive damage to occur under these conditions. I have taken them out only once to play and rip them. When I bought them they were in excellent condition and I have kept them that way as any serious collector would.
Look at all the other tapes I have sold (some of the rarest sold for years on ebay) and I only have 1 of each these tapes. I have sold about 50 tapes so far and no one has had any questions about authenticity.
I know these tapes come up very rarely especially in this condition and I know there are loads of modern day re-presses, so I understand why you might question them.
If you have any more questions let me know and I will try answer them as best as I can.