I had the same bad experience with CEX.IO :-(

CoinCorner has similar requirements, never succeeded to finish the verification process.

I could think it's all due to their UK jurisdiction, but Coinsbank is also British, but I had no problems with them, as well as with US Poloniex.

So I think all those requirements are CEX.IO (&CoinCorner) understanding of KYC practice.

By the way, once I made online payment with the bank card and was asked to upload video selfie with the card, saying something! - I cancelled the purchase >:-(