* Tesla produced ~250k vehicles (cumulative as of Q2 2017) prior to the first production Model 3, so it's not appropriate to compare them to a brand new company: They know how to build cars by the time Model 3 rolled around. This is their 4th vehicle model.
* Tesla has stated many times how the Model 3 is a far simpler and trimmed down vehicle compared to the S or X: production should be easier.
* Tesla had a goal of 2,500/wk by December 31st (they managed 793 the last week by shutting down S&X production) and a total of 2,425 for that entire quarter.
* Tesla had a goal of 5,000/wk and a revised goal of 2,500/wk by March 31st but only managed to hit 2,020 by that point, again which required shutting down the S&X lines.
* The new goalpost is 5,000/wk by June 30th.
* Elon said that "excessive automation at Tesla was a mistake" and that "Humans are underrated". [1]
If Musk himself is suggesting that the Model 3 delays would have not occurred due to human assembly instead, I think it's quite fair to compare against Ford's Model T assembly line a century ago. Not to mention a few advancements in technology since then which should give Tesla the upper hand.