Its asymmetrical warfare mate. Labour are up against a divided voter base (the left vote is always split, plus the Brexit divide although I think that is receding), a toxic, well funded, right wing press that fills people's heads with absolute horseshit, and most of the rest are 'pliant', general voter apathy, but worst of all a tory party that values ignorance and just flat out lies now, relentlessly. Its extremely hard to challenge that.
I'm an auditor. When I go into an organisation there's rules to the game, you'll know this from what I know of your background, those tacit agreements and ground rules. If I finished an engagement, gave the organisation a report and said 'my team found this, this and this... you're carrying these risks and here's how you improve' and they turn round and say 'no you didn't, and all of that evidence doesn't matter, and anyway its all someone else's fault...'
Where do you go from there? How do you have any sort of engagement with people whose standard behaviour is to just deny objective reality and blame everyone else when they've been in charge for over a decade.
I'm not saying its impossible, but Labour have got the odds stacked against them before they even get on the field.