To answer your request, let's follow a logical train of thought (this is the best I can do). When a robot produces value in the economy, it will be considered production and therefore not subject to taxation. Only humans can consume, and as a result, only humans are taxed. However, if humans do not produce, what will they use to buy and pay taxes? This shift in emphasis means that the focus moves away from who creates the value to who owns the units that generate the value. In a scenario where robots create all the value, humans cannot solely rely on selling their labor and must shift their focus to owning the means of production. Now, humans need to buy and/or create the units that produce, and because they don't have to pay tax on it, the motivation to do so will be high. These are my thoughts on the matter. Taxing consumption can still be effective.