[dottrap]

Lua IS a register based machine. The white paper done by the Lua authors is the reason most of the industry has moved to register based machines. (Apple SquirrelFish for Safari was the first to read it and implement it and everybody followed suit to compete.) http://www.lua.org/doc/jucs05.pdf

Lua has true multiple return value support. The overall usefulness of tuples in light of this feature is not clear.

Lua has first class support for functions and actually supports functional programming unlike Python which cripples many techniques and where Javascript has broken lexical scoping. Lua uses metamethod programming to allow you to build functionality like classes; Javascript has prototype inheritance which is different than Python's classical inheritance. Each is just different; not necessarily more or less structured.

Also, never confuse simple for being primitive. Lua IS incredibly simple and elegant. But all the simple things in the language work together elegantly to allow for amazingly sophisticated things.