Note the Eurostar is perhaps an especially bad example in terms of affordability, versus most HSR in Europe:

* the Channel Tunnel has very high access charges (because construction was very expensive, and as a private entity it took on a lot of debt and wants to pay that off!), and

* the terminals in both London and Paris are too small for the time taken by border control now the UK is no longer in the EU (which has led to Eurostar running fewer trains—but the demand has hardly decreased).