I'm going to cover off a few of the points that
@aron2smith has said in recent days.
Now, it is entirely understandable that someone living in Hertfordshire and outside of TfL's area will look enviously at the number of red buses and the evening frequencies and say "I'd like that where I live". I think we'd all love more services and at more times. However, we look at the figures involved... TfL subsidise the bus operations to the tune of c.£800m IIRC. That's about the same as the rest of England, I think! It's often sold by politicians (espousing franchising) that they can deliver a London style network yet the costs are never explained. And remember, this is with a level of cross-subsidy from the very busy London routes...something that places like Hertfordshire can only dream about.
The rose-tinted view of London Country and the NBC in general also needs to be put to bed; there are myths that simply don't bear close examination (and the poster is not the first person to say these things) to the reality especially from those who were there at the time. The NBC was heavily loss making through much of the 1970s. The reason why it ceased to be and was more self sustaining in the 1980s was that it instituted some massive cuts to services and depots through Market Analysis Projects. Much of that was focussed on the more rural parts of LCBS as I'm sure
@greenline712 would testify. Also in that time, the reduction in the Green Line network took place and into the 1980s. The reason for that - increasing traffic congestion (since the 1950s) was making services unreliable and slow and, let's be honest, British Rail was pretty moribund. They got their act together, with Network SouthEast and then into the franchised world, and rail services are considerably improved since then. The wish to travel from Broxbourne to Enfield. Well, the poster may wish to make that journey, and it's frustrating that they can't. However, is that a major flow/traffic objective or personal preference? In fact, looking at the 1965 London Country timetable, that wasn't a journey that was available in those halcyon days. The fact is that if there was a major flow there, someone would be in there and doing it. I think that's it as regards the wider issue of bus service ownership and control (and the history thereof).
Onto the subject of Arriva. Much as though they were woeful in many respects, the old Central Connect were not averse to steaming in when Arriva withdrew on corridors like the 420 (now 20). Now it is absolutely fair to highlight that CC were poor, and that Arriva ceded territory in areas where they should never have been in that position. Arriva were hamstrung by unrealistic margin expectations from head office, compounded with a massive belt tightening on capital investment as DB's debt pile increased. So effectively, you had a board in Germany who were ultimately responsible for authorising investment - do they use the limited funds on a guaranteed 6% return on running river boats in Copenhagen or a higher risk 10% on some buses in Hertfordshire? I think we know what happened.
So what happens now? Well, you have a new owner that does have access to more funds in iSquared. They are a private equity fund and, lord knows, we've seen some bad ones in various other industries. iSquared tend to have a decent record in long term investing and developing their business. A lot of questions were raised about Arriva not bidding for Manchester, and the exit from Bucks and Cheshire, and that it was iSquared exerting their influence. In reality, it was a hangover from the dark DB days. However, it will be a long way back for a business that has been starved of finance and the freedom to innovate over 8/9 years. I was warning about this in c.2014 when it was far more fashionable to slag off First.
There are the first signs of change - a slight loosening of the commercial shackles, a bit of targeted investment. However, these are issues that have been years in the making so don't expect massive investment. It's a long way back and, as befits a large organisation, there will be differences as to how OpCos behave. Unless you rule by diktat, giving management teams freedom to manage will highlight regions that have a more cautious or conservative approach than another. Not everyone is an Andrew Wickham (god rest) and even in Go Ahead world, you have the good (GSC), the bad (GNE) and the ugly (Go East Anglia).
For the first time in a while, I think it might be interesting to see what Arriva actually do.