For those who don't think railways benefit them, I'll ask you a question which is likely to carry more people the busiest bit of the M25 which sees AADT (2 way daily traffic) of 200,000 vehicles or a railway line operating for 16 hours a day (06:00 to 22:00, so probably longer but with let frequencies towards the outer edges) with 17tph (so loads less than say Thameslink) and with an average loading of 550 passengers?
It's a bit of a trick question, as on the numbers the answer would be about the same (assuming 1.5 people per vehicle).
As such even small reductions in rail use would likely have a big impact on road congestion.
How much of a drop in road use is there between term time and school holidays? 25%, 35%, what?
Actually again it's quite a lot lower than most think, it's about 10%.
Now given that rail accounted for about 10% of miles traveled, adding that to school holidays would make it comparable to term time, add it to term time and the roads would grind to a halt.
It's the same with cycling, car drivers benefit from everyone who cycles rather than drivers.
Therefore, regardless of if you use rail or cycle you still benefit from it. The problem with cutting rail services is that either you accept that you've got to provide subsidy to it or you've got to plan to close it down.
Whilst over the last decade the Net subsidy had been running at about £4bn to 5bn of you excluded the cost of enchantments from that you typically had a value of noticeably less than £1bn.
As such, for the next few years, unless the enhancements lead to significant savings (either in cost and/or carbon) then chances are they could be put on hold for a while and the Net subsidy cost probably wouldn't be so that much more.
If there's other cost savings which don't harm services too much, for instance a rolling out of more remote ticket sales machines (a member of staff in a central monitoring location and instruct the TVM to produce the required tickets, but can cover several stations) alongside don't things to encourage an increase in rail use. Then the overall picture could be not too bad.
On the fact of ahigher than expected fall in rail commuting and little sign of our rebounding from 70%; it should also be remembered that one thing which wasn't anticipated was the quite so significant fall in people working, I suspect that anyone who was thinking of retiring over the next 2 years and maybe even up to 5 years if they were put on furlough (and if they were made redundant almost certainly did) would have thought very hard about going back to work with many deciding to retire. As almost whatever industry you're in there's a shortage of staff, be that hospitality, engineering, lawyers, lorry drivers, etc.
The impact of those retiring would have been made a bit worse by the fact that it's harder to attract EU candidates.