Multiple TOCs▸ run from Oxford to Reading without issue - there is no reason why a line should have a single TOC. If airports were run like railways you'd have one runway per airline.
I would dispute the conntention that the multiple TOCs run between Oxford and Reading without issue. There was contention even in
BR▸ days between Inter City, Cross Country,
NSE▸ , Freightliner, Aggregates, Oil etc. freight sectors. But at least they were basically worked by BR and the signalmen were also BR and their was a Fat Controller (General Manager) in Paddington to bang heads together when things got out of hand.
As one of the staion supervisors at Slough said to me soon after privatisation that there was now no way he could bag a loco from Langley oil terminal to push a failed train out of the way as he could in BR days. He couldn't even issue a special stop order without express permission from Thames control at Reading.
I would suggest that it's even worse now because of the late penalty system that, as we've seen from many posts on this board, sensible train regulation has gone by the board. No TOC is going say you can hold my stopper for 5 minutes and let buggins late running fast in front. No the stopper will run on time whilst the fast gets later. Also the signalmen are Networkrail now just signal the trains as they turn up they are no longer allowed to make regulating decisions without consulting all the controls involved. Which takes too long. An aphoracal story suggests that on Sunday at a large junction staion a train from one operator running on time but with a booked stop of 15 minutes was allowed to occupy the platform whilst another late running booked in front of the train ocuppying the station was held outside waiting for the platform to clear.
Having observed and reported on train regulation in several boxes on the Southern, I know in that real time just how quickly regulating decisions have to made if you are not to delay a whole sequences of trains.
That's why rail on rail competiton is not the same as many airlines using the same runway. If planes are late off the terminal other planes can have taken off in front off them and they can take their turn. Although they might technically delay a following flight, if you look at airport depature boards you often see several flights with the same depature time, which of course is impossible. Once airbourne they are usually free to fly to their destination without much disruption, as they are not flying in the same part of the sky as the plane in front. Whereas, trains have to follow on the same line so if the train in friont stops at a station the following train has to stop behind it.
Also air timetiables are subject to even more padding than train times.
So by and large Rail on Rail competition is extremely hard to achieve, although as Hull and Wrexham Shrewsbury have shown they can provide a better services than the major TOCs on their routes. However, to make the railways work to their very best overall there has to be a Fat Controller in overall charge and thinner controllers in charge of specific smaller parts of the system, who have absolute control over everything that goes on between the boundary fences on their length of line. Oh dear I've seem to reinvented BR or at least
GWR▸ for our lines.