Don't forget about quinceañeras, which are often quite lavish affairs.
Speaking as someone who spent 8 years at a Jewish university and then moved to a heavily Mexican neighborhood, I would tend to agree that there are lots of similarities with a Quinceñera and a Bar Mitzvah, despite the difference in age and gender.
Growing up in a middle class St Paul suburb I didn't see anything particularly special with Sweet Sixteen in the 1970's other than the use of the title, sometimes the party was a bit bigger, but often not. Neither of my kids were particularly interested making any more of a deal about their 16th birthday than their 15th or 17th ones.
