The train is the most convenient method of mid distance inter-city travel in the UK because it’s so fast. Nobody’s driving the 4 hours between London and Manchester, Liverpool or Leeds for a business meeting when the train takes 2 hours.
Inter city trains in the UK aren’t running on dedicated high speed lines - they’re Victorian routes, pass through plenty of stops on the way and are generally 2 or 4 tracks.
They do have priority over freight though - which along with incremental upgrades over decades means the trains can run at 125mph for parts of their routes.