Carlos has an awesome account (pic). My driver list is above (>>1636272 (You)) for comparison.
Carlos has 80 Lv8 high end drivers! It looks like a lot of the non-Mii's are just unwanted things that he kept getting in pipes but never uses.
As you mentioned, I'm surprised he's not invested in either Astro Toad, Wiggler, or Toad Tourist for Luigi Raceway R/T. However, Pink and Purple Mii suits are useful for the hard-to-cover GBA Peach Circuit R/T in ranked for the Vacation Tour, as mentioned above (>>1643732). If Carlos pushes me hard enough, I might be tempted to pick a Mii over Astro Toad and dump a bunch of tickets on it.