I thought there was a queue of people wanting to work on the railway, whats the wage for a guard on Northern at Barrow, I might be mad enough to consider moving up there!
One of the big issues Northern has is training capacity and like @
lrailadventure says a not insignificant number of people jumping ship, or retiring. A training group for Conductors is around 2-3 months before they go off to their own local depot. I believe they can have up to 4 concurrent training groups at most on the East side, with around 12 people per group at a maximum. This is to cover all depots on the East, so from Newcastle, to Hull, Leeds, and Sheffield, I'm aware Leeds specifically is haemorrhaging staff with some trainees dropping out before they have even worked a train solo.
A shortage of conductors and a shortage of drivers ultimately leads to where we're at right now, and it's not looking like it will get better anytime soon.
Northern has the luxury of running so many services and over shorter distances that it usually just impacts local people, TPE is more an Intercity operator with fewer services and a more noticeable impact across the country when they cancel one. A local newspaper/media outlet may pick up on Northern cancelling every service to their area, Morecambe, for example, but it's only the local media that will care. TPE would get the attention of Manchester, Leeds, York, Newcastle media outlets and then ultimately the national media outlets/newspapers pick up and started reporting on it. Northern is arguably in a much worse state than TPE was, and in my own personal opinion, Tricia Williams who will be taking over next year will only see to make things much worse as a DaFT yes person.