Broadcasters have to pay to access Freeview (which is owned jointly by the BBC, ITV, Sky, Channel 4 and the transmitter company, Arqiva), as well as for the actual content that they transmit. If the additional advertising revenue they get from broadcasting on Freeview doesn't meet those costs, they simply cease using that platform:
https://uk.motorstv.com/get-motors-tv
Commercial broadcasters generally operate on a shoestring budget. With many advertisers switching their expenditure from TV to web advertising (especially via social media), at a time when there are far more commercial companies than there used to be, each broadcaster only has very limited income. (The 'real terms' advertising revenue that ITV gets had fallen by over 90% since the days when there were just four channels on air).