[brabel]

If the system is just at capacity, but not beyond, it’s in fact well optimized. Empty trains are a loss to the company running it. Similar to airliners: they want every flight as full as possible. No company cares if it’s comfortable for the passengers since they either have no competition, or if they do it’s always the one offering the lowest price who wins. The passengers who want comfort can buy first class for a gigantic premium, and that is also well optimized: expensive enough to be profitable, cheap enough to actually sell tickets.

[physicsguy]

There is no "company" in effect and hasn't been since 2020. The government is the operator and tells companies where they can run trains and what they charge while the companies have levied a % of revenue. That's changing as the government is now bringing operation back in house as 'Great British Rail'.