I think we're going round in circles.
Indeed we are
So you finally accept that if people board a train without any reservations in force, then they are not "ignorant" and they are acting in good faith by sitting anywhere, in accordance with FGW policy, and what
most (not all) people on this thread believe is acceptable. Good

We can move on then!
Ah I see. Regardless I don't see why we should.
So you keep saying, but the reservation charge really isn't anything to do with the matter at hand. There are plenty of ways to avoid the reservation charge anyway (book at a non-FGW station, get your reservation when you buy the ticket, etc).
Whilst on this topic, if I asked for a seat reservation when I made a booking for a Day Return would I get charged? (if the £5 policy was absolutely compulsory).
You had earlier quoted both
ainsworth74 and
Island informing you of this:
FGW's policy is to charge £5 per seat reservation not made at the same time as purchasing the ticket. I don't know if that's applied in practice.
It's not; well, as far as I can see. I've always gone and made seat reservations and I've never been charged once, and so I shouldn't, quite frankly.
So I'm not quite sure if repeating it again will help, but I will try, one final time:-
It is FGW policy to charge for seat reservations if you are
not buying the ticket at the same time, except in certain circumstances (as mentioned by Ainsworth74 earlier).
So, no charge if you are obtaining the reservation at the same time as buying the ticket.
It is not "compulsory" but it is their policy, so it will depend on the discretion of the clerk. If you go to the clerk saying things like "I don't see why I should pay for a reservation" I would suggest the clerk is less likely to show discretion and waive the charge.
On nearly half the trains between Cardiff Central and Bristol Temple Meads, you can't get a reservation because the train company doesn't offer them.
Reservations are available on the 0628, 0730, 0830 and every 30 past until 2030 from Cardiff and from Bristol on the 0754, 0854 and every 54 until 2254. So that's quite a handful, in fairness. That's thirty-one trains.
Yes, as
John @ Home said!
...but when First Great Western think three carriages is appropriate on the 4.54 BRI - CDF, then it's a different matter!
FGW "think 3 coaches is appropriate on the 1654 Bristol to Cardiff"? Well, that (false) claim sounds familiar... Ah yes, you made that claim a few days ago.
BestWestern explained the situation to you, and you replied saying "fair enough":-
For example, I travelled on the 1654 Bristol TM to Cardiff service around two weeks ago with a friend (I think we had reservations in Coach B, seats 79 and 80, IIRC). This is a VERY busy train, which FGW still insist three carriages is enough – the answer is it’s not, quite frankly, but that’s another topic and irrelevant to this case.
FGW don't insist anything, they use what rolling stock is made available to them, as with most other TOCs. This has been covered many times before!
Fair enough. I've heard previously that there's a national shortage of carriages but how come the 0730 from Cardiff has a 150 attached as far as Bristol and how come the 0600 Portsmouth to Cardiff has a 153 attached between Westbury and Bristol? Also, I've never heard of what's being made available to them.
Have you changed your mind since you accepted that explanation? If you wish to discuss it further, as I said before, create a new thread in an appropriate forum!
They don't 'think three carriages are appropriate', they had many of their 158's taken away from them.
Really?! Dear me. FGW's Facebook page is full of their customers telling them how overcrowded their trains are!
Yes, really! I do not think the DfT, who decide rolling stock allocation, are going to be too fussed over people complaining on FGW's Facebook page, especially given there are similar complaints by customers of other TOCs (e.g. Northern).
If you wish to discuss this matter further, I suggest either locating an existing thread (there are many) or perhaps creating a new one. I think you'll find plenty of reading material on the subject already!
Can we
please not go round in circles on any of these issues again?