> - filing taxes for each machine (companies may have millions of machines)

Yes. It may be harder to figure out the definition of a machine - e.g. a computer can have multiple programs running, is it one machine? - but this is one direction.

> - determining how much income all machines make

Yes, it's tricky, but we can try. For example, some temporary measurements which can be updated every few years?

> - taxing cloud usage

Yes, we can measure power, bandwidth, network sessions for that.