Italy has the concept of competition on the same route - at least on long distance routes, Italo compete with TrenItalia. The result is cheap, pleasant long distance service. It's a much nicer model than the UK has, certainly.
In the UK, you can buy expensive, flexible tickets which are valid on any train and any reasonable route, or you can buy cheaper tickets with various restrictions, typically one or more of:
- Valid only on a particular route/operator
- Valid only on off-peak services
- Valid only on a specific train/time
- Must be purchased a certain period in advance (usually by the previous day)
However, in the event of significant disruption, and trains are running late or cancelled, an announcement is usually made relaxing the cheap ticket restrictions. At the very least, if you have a cheap advance ticket and your train is cancelled or delayed, then you're allowed to use it on the next available service, regardless of operator.