"Some people don't like the alternative systems used in Europe. "
When you get on a TGV, there are no reservations out, as they are mandatory. But you can get one from a machine, even a few minutes before it leaves, and at intermediate stations as well. Its non chaotic.
What we have got here is an indefensible position, in that what should be a rare exception - no reservations out - is a regular occurrence. So I agree little else can be done in the circumstances***, but the circumstances arise far too regularly to believe they are being properly dealt with by the TOCs.
There is another Virgin variant on this - regularly seen at Euston - where the reservation signs are blank from the first people to board until a few minutes before departure -resulting in people having to shuffle around after they have settled in. (usually full fare payers).
Remember also NRCoC condition 41 - you can get a refund of the fee, as this is usually zero not very helpful, and 42 entitles you to compensation if no equivalent accommodation is provided (up to the value of a single). Its not clear what compensation applies if you spend a journey seat hopping, but you would certainly expect something if you had to stand for all or part of the journey.
***Edit - although on Cross Country I have sometimes seen reservation tickets printed out from the ticket machine being used when the electronic system has failed
