Because Lua's Hello World is just `print("hello, world")`, which looks a lot like Python and doesn't tell you much about actually using the language.
Look at the Go homepage. Or Nim. (But not Rust sadly.)
function fib(a)
return countfib(1,1,a)
end
function countfib(a,b,n)
if n == 1 then
return a
else
-- proper tail call
return countfib(b,a+b,n-1)
end
end
print(fib(6)) --> 8