Trainline charges fees on about 1/3rd of the tickets it sells, in addition to the 5% commission it earns.
So I was surprised to read the claim: ‘You won’t find cheaper tickets anywhere else.’
Oh yes you will.
Just choose one of the fee-free rail firms/retailers.
https://www.independent.co.uk/travel/news-and-advice/rail-ticket-trainline-cheap-fares-fees-b2699505.html