I think this is a British-ism. I'm British. The parent's post used tariff in a way I found normal. Google tells me:

  tariff - noun:

  BRITISH
  a list of the fixed charges made by a business, especially for use of gas, electricity, or a mobile phone.

In American english tariff is usually used as "tax". Especially in the context of import & export taxes on goods and services. (E.g. The American colonies revolted over the tea tariff.)

Indeed. Tariff is a dirty word in American English.

Fwiw US telco-speak still uses tariff to mean price.

Sorry for the confusion, I think the correct term is 'hourly rate', what you charge as a consultant for your time.