Honestly, I think this failure runs deeper than something like whether it's privatised or nationalised. These services were mostly rubbish when they were nationalised and they're still rubbish now under privatisation. Nobody sane thinks the era of privatisation is any good in my opinion, but it's not like what it replaced was exactly well-managed. We had things like the Beeching Axe in that era which absolutely screwed over many non-metropolitan communities and continues to even today especially in Wales.
The UK for the best part of a century has never been good at public transport on a national scale. Public or private, profit or non-profit, every single attempt to make it less of a skip fire has ended in failure. I think the only way we're going to see improvement is if we start looking at the root causes rather than ideologically-motivated political solutions. This isn't a political issue, it's a geographical and an engineering issue.