The always peak time cost for the Zone 1 to Heathrow underground stations is imposed by TfL, but was effectively part of a requirement to raise additional revenue strongarmed on the mayor of London by the previous government to assist with operating costs for London's public transport in the post pandemic recovery period. Unsurprisingly the always peak cost is here to stay.

The additional costs on HEX and the Elizabeth Line into Heathrow are as I understand things partly a levy made by Heathrow Airport Limited who own the tunnels that provide the access for the trains, and partly by TfL.

Additional costs to/from the airport are mainly targeting discretionary travel or non-residents and are considered a soft target politically. Airport workers can still use the underground from non-Zone 1 to Heathrow at the usual costs, and there are a number of targeted transport schemes for Heathrow Colleagues.