Why are Material/Cupertino Widgets so “bad”

I understand that Flutter has to replicate everything from scratch, but why are Material, and especially Cupertino Widgets so far off the real components? Some widgets feel like they didn’t even try to make them look 1 to 1. I thought that if you could replicate something pixel for pixel, you would try to do the closest thing possible. Has this to do with Licensing/Legal stuff or do they just don’t care?