Are there really many differences between modern watch movements?

[goliat]

A lot of it is due to pure man-hours and branding/marketing. Finishing is usually secondary.

Like in pretty much everything, after a certain threshold you begin to see diminshing returns. Small technological leaps have huge cost increases. You will see a significant difference between a $300 Seiko and a $2000 Oris, but there the curve starts to flatten a bit. For example, there is virtually no difference between a Tudor in-house movement and a Rolex one other than the "superlative chronometer" label as per Rolex standards - both do little to no finishing and generally the movements are ugly af.

Personally, I think Grand Seiko's Spring Drive is the greatest movement ever created and holds the most bang for buck (alongside their 9F quartz movements).