That is a "trick" from the casino as most casinos use this in order to just delay the funds so you can play again and risk to lose it all,we have all heard stories of this type.
Too many. The statistics they must have on how many people lose their earnings it they make them wait in order to complete the withdrawal must be overwhelming. That's why they do it. Instant deposits but delayed withdrawals, which are delayed the longer the larger the amount. It is true that for security reasons it is better to review and not allow instant withdrawals of large amounts but this and other cases are way out of line.