'I guess it's more a case of a lack of suitable applicants who were also prepared to pay for a type rating and/or be bonded and/or be on a crappy 70% contract.'
I was one of the very early casualties of the last recruitment drive who gave too many 'no' responses when they were (at first) playing hard ball with regard to the factors mentioned above. I'm sure many other capable and suitably qualified people, who stuck to their guns, also fell by the wayside.
I spoke to their very helpful HR department last week and was told that all recruitment for this year was complete and the next 'drive' would start towards the end of the summer. I was invited to reapply when the system was up and running.
It would appear that if you went out at that awful phone interview stage there appears to be no reason recorded by Jet2's system as to why your application was not progressed.