I don't get your maths? [1] 160/9 months != 600 for any given number of days a week e.g. 5,6,7 (something between 6 and 7), but where did the 9 come from, is it some kind of adjustment for weekends? Anyway there is also a concept of "fully loaded employee cost".

In any case the way to think of this is not "/day".

The reason is simple. If you buy 1000 barrels of oil, you buy 1000 barrels of oil not 17.4 days of oil. There is now a disconnect between work done and time. Infact you would be sane if you said "that result I can get in 2 days for $4172, if you can get me that same result in 1 hour, I'd pay $8344". See where this is going?

Yes a lot of thought work is now a commodity, and if you want the commodity faster (last minute booking, uber to come quicker etc.) you pay more not less. Value being $/hour is over.

[1] The ? acts as both a question and a regex.