I mean of course, that's why I'm kind of in two minds about it. On the one hand, Trenitalia and Italo's competition have made Italy's high-speed network better, and the Madrid-Barcelona route has given passengers four options between AVE, Avlo, Ouigo and Iryo. It can make passenger services better,
There is nothing like a bit of competition on quality front, which of course tends to weed out the rubbish offering as poor quality or value
but in principle I also believe railways are a public service first while open access will merely cherry-pick the most profitable routes.
To be fair, some of the current nationalised operators do cherry picking too, putting better, or newer, or faster rolling stock on some routes, or giving better catering on selected routes, even beating those of longer duration than some others they operate.
As an example, there is no logical reason (apart from selective cherry picking) why a London Lincoln service, gets First class with free food, but Bournemouth (whose population is almost double) gets no food, similar duration (about 100 minutes) both DfT Operator administered. It's blatant selective cherry picking by route.
Having recently returned from Switzerland which practically has no open-access operations, competition isn't an absolute necessity for a better railway.
Switzerland is different, it is happy to spend to sort bottlenecks, or add spurs, tunnels and flyovers so service patterns can reflect 21st century population, leisure and workflows.
Many UK operators still have services that are similar to decades ago, even if population has relocated, or work or leisure destinations different. And seem to be stuck in a rut, with no intention of swapping a service from A to B and C to D to one that is A to D and B to C even if that's now popular Route.
I am all for Open Access filling in gaps, if the State can not be bothered to serve them. Not reckless duplication, but reasonable expanding into unfilled routings, thus increasing overall revenue where competition is currently no journey by train because too difficult / slow / requires changes etc