urpert
Member
It's a good question. One possible factor might be is that apart from London and Manchester, most British cities have a commercial centre and the predominant residential area is the suburbs, so there are fewer opportunities for people to pool car trips from centre to centre. But on the other hand that would handicap trains too.
Another possibility: the UK benefits from extremely low train fares for people who are willing to give up their flexibility, and maybe this is what has headed off the blablacar competition.
Not convinced about the latter. I’ve never had any more difficulty finding advance/Prem’s/Sparpreis/whatever tickets with either DB or SNCF than I have with long distance journeys in the UK.