yep, but as others say, you run a whole ton of draw spells and selection spells, and you run a deck with an average cmc below 2 probably (I have seen some decks go up to 2.5, but those often run 30 lands and not 28 like the super sleek ones). And one thing people often ignore: if you add up the mana sources in a cedh deck, you probably end up somewhere around 45 up to 50. Because despite the super low land count, you will find all the efficient rocks and dorks and land enchantments and whatnot, that help you to give you the needed mana. I might even go as far as saying that many cedh decks run more mana sources than many casual decks.
If I budget down a cedh deck, if I take out a super efficient mana rock, I don’t throw in a bad rock or value spell, I thrown in a land at first – it is crucial to hit your mana. You can get away with low numbers of lands, if you bring in two mana sources (a land and some acceleration) every turn, because if you end up with 6 mana T3, you are probably much better suited than the casual deck that played a tapped worn powerstone at that turn. And some cedh lists have quite a bit more than just 6 mana T3.
BTW: that’s why Pyroclasm can be the worst thing happening to a cedh deck in the current meta, it wipes out the dork based mana. Of course a cedh deck not only has the fast mana, it also has the fast interaction, so don’t just assume slamming a T3 pyroclasm or Anger of the Gods will resolve 😉