That's just an excuse.
The "network" involved in a journey from Manchester Piccadilly to Manchester Airport is not complex. There are no alternative routes one might reasonably consider taking. Yet because there are three operators involved there is an astonishing array of tickets on offer. TPE only, TfW only, on-the-day advances for Northern or TfW, Airport Advances for TPE (which in the event of a delayed flight can be used on a later train operated by TPE, Northern or ERM but not TfW) and the choice of an Anytime or Off Peak tickets for the various operators which might be valid from 0900 onwards or only from 0930 until the evening peak. All three operators are nationalised so everything ultimately goes to or comes from the Treasury anyway. You might argue that journey planner ticket issuing systems make it easy for the passenger to choose which time to depart but anyone familiar with platform 13 at Manchester Piccadilly will know that trains almost never turn up at the advertised time. Bear in mind that most of the people going to Manchester Airport are not regular rail travellers and many will be foreign nationals.
The network there isn't complicated, the tickets between these two locations have been made complicated because it suits Pricing Managers to have them so.
It may be simple but having to pay double for a ticket from Holyhead to Oxford when travelling on the 09:23 which doesn't even get near a Voyager until gone lunchtime is ridiculous. Scotrail simplified things properly. The day that Voyagers are replaced by proper trains on XC and the fares dropped to sensible levels I will throw a raucous party.
Yes, like the Swiss Half Fare Card. No silly rules, no odd discrepancies between 16-25 and 26-30, no giving discounts to 60 year old Finance Directors while making the minimum wage intern pay a minimum fare. Just have a national railcard available to all (other than the Disabled one which should differ by allowing a companion). You can discount the purchase price for students or pensioners if you like, but as soon as it is paid for it is a standard product.
It would be a lot easier to teach if there was less to cover. On my Guards' course we spent an entire day on railcards and all the differences between them. If we didn't have to devote that day to that aspect of complexity we might have been able to devote some time to what can and can't be excessed.
By far the most likely outcome is that all of the operator specific fares except for Lumo, Hull Trains and Grand Central will be withdrawn in the near future. For most journeys in England there will probably be a single at about half the price of the Off Peak Return where currently available. There probably won't be any Advance tickets available at all on the day of travel for journeys in the pay as you go areas.
Now you say it's a political choice what level to set the simplified fares at, and that's correct. But for practical purposes where can that fare be? In the case of Manchester - Chester it will probably be a flexible single for about £13, with some similar prices for Advance tickets to today but in much more restrictive quota. If you made it about £5, which would be where I'd put it then you'd never deliver the capacity. And that's pretty much exactly the same as every other regional route in England, we don't have the capacity. I get that it's nice to
imagine that the government would support a single low price single for that journey, but they won't. So any simplification means much less efficient revenue management: your choice is busy trains being so busy that people are standing in the aisles and at risk of being left behind, or trains during most of the day with vacant unsold seats.
In Scotland, rural lines generally haven't benefited from the recent simplification and reduction, and there's barely any commuting going on trains to Aberdeen (don't @ me if you are one of them). So it's only really the central belt commuting and AM peak long-distance that got a price cut. And the Scottish internal long-distance market is pretty small compared to England. So really this trade-off was only present in Central Belt commuting markets - where they already have expanded capacity significantly recently.
In Belgium, a single low price single for nearly everybody works well. But that's because they offer enormous capacity, most of which spends most of the day running around completely empty. That's a great way to solve the issue at hand, but unfortunately it's the equivalent of many hundreds of billions of pounds of capital spending on modern infrastructure which the Belgians have been spending and the English haven't.
So while it's easy for train conductors to whinge that it's all the pricing manager's fault - it's actually down to their revenue management expertise that the industry has grown as much as it has in recent years, and has weathered a pandemic far, far better than it would have done if it'd been happening in the late 90s when most tickets were just single or return and that was it. The current set of rules is rubbish but the new one is likely to lead to faster and peak time trains becoming more crowded than today, and slower trains or ones at the extremes of the day have even fewer people travelling on them than today. I don't think anyone wants that, but that's the likely outcome.
West Midlands Trains have pushed back very hard to be allowed to keep their operator specific fares. Frankly it's a relief that they've made the effort when most of the rest of the industry seems to have given up. Anyone who thinks it's sensible for the London - Birmingham stopping trains to cost the same as Avanti on the day of travel is kidding themselves. Especially when Avanti is like London - Newcastle is now.
A lot of people will see the price jump overnight by between 50% and 100% when the operator specific fares are withdrawn, and the Advance tickets are never avaliable on the day of travel any more, and realise quickly that the only way they can continue getting where they need to be at a sensible price is to get (another) car.