Tested this out on Postgres and it works:

  SELECT
    name, count(1)
  FROM 
    (VALUES ('Kev',12), ('Meg', 14), ('Kev', 14)) 
  people(name, age)
  GROUP BY
    1

Produces: [[Kev, 2], [Meg, 1]].

But I don't get it. Could someone explain how this works?

Please never allow this into production. I believe it is deprecated, it certainly is fragile in general.

I actually find this less readable. i have to go back and scan the select to see what column this index corresponds to. Totally breaks the flow of reading.