From an initial speculation on the subject, I don't believe we should tax robot workers, on the basis that it would be too difficult to logically create legisla

From an initial speculation on the subject, I don't believe we should tax robot workers, on the basis that it would be too difficult to logically create legislation for, especially considering the tech-knowledge of our legislators. How would we measure? If it's per-robot, businesses would just figure a way of linking the computers together and calling them 'one'. If it's per-output, then what is a 'robot' vs computer/software, that exists in virtually every business already? Would it be fair giving small businesses another tax, for investing in computers and technology instead of human manpower?