The taxation of non-cash income has been a settled issue for decades (in the US).

They would tax Bitcoin receipts the same way they tax service-for-service or service-for-property exchanges. The government will calculate the fair market value of the services/property received at $X dollars (based on facts and circumstances such as the amount exchanged in similar cash-based transactions), deem the taxpayer to have received $X in income, and impose a tax of $Y on that deemed income.