Well, in the last year LNER has been the only operator I've travelled upon, and their reservation policy has been a light to the rest of the railway world IMO.
Most of my journeys are for work, like as not Newark-KingsX going somewhere in London or beyond.
My employers have a fairly strict COVID-safe travel policy at the moment, as it did straight away last time (our management saw the writing on the wall and sent vulnerable staff to work from home 2 weeks before 1st lockdown, and the rest of us a week before - well done to them!). The upshot of this is that we have to be able to demonstrate that safe distancing & working is in place all the way from base to site, on site, in hotels, and back again. So if I would have to used the Tube from Kings Cross, for example, that was unsafe at peaks so it was a case of driving and staying over in a safe hotel. But some sites have been 'walkable' from Kings Cross, and it was great to be able to take the (much faster) train again, knowing distancing controls were in place.
Coming back to the point, the LNER practice of ensuring all are correctly seated and 100% reserved - for the most part - has been a class leader in rail. Would I travel on Transpennine "we're trusting passengers to distance" services? No thanks, unfortunately a significant minority can't be trusted to do that. A shame really. Now of course, there are times of disruptoin [most notably the great cracking debacle] that makes reservatoins and distancing impossible to deliver, but in all honesty the operator and its staff have always provided the best customer service that could have been hoped for whilst doing their best to also keep us safe. Other operators could have looked to this.
With a few notable exceptions, this has been my long-term experience of staff on the East Coast. Even when National Express tried to break it the staff carried on trying their best to deliver the customer service attitude already established, often with a wry twist or friendly honesty, but never unpleasant (if occasionally a bit tired and less interactive as a result, but hey, they are humans!).
Yes, distancing is not going to be perfect, but the principle keeps the number of people in a closed space controlled, which reduces overall risk of airborne transfer. it's not jsut about proximity, but also density (and yes, i've been accused of being dense but that's another story...) Hopefully one day soon the distance and space really won't be needed and we can have more travel capacity, but for now let's not rush the finish and regret it later. Patience please for as long as it takes! One day relatively soon we'll be able to hop on a service as we please (with the right ticket), and it'll be great, let's look forward and see what shape that future under GBR might take while we wait for the long tail end of this crisis to unfold.