We definitely disagree about what child led versus parent led means as a whole. I know I'm not the first to say that I honestly don't understand the point of EC. A child at 18 months is vastly different in cognitive ability, lack of boundary testing and independence, etc., than that of a 2-3 year old as those skills aren't really developed yet. It's not so surprising to me that something such as this becomes just another way to try and assert their own independence. It seems like too much work for negligible results a lot of the time. Like you said though, maybe your son is more suited to it than your daughter. How old is your daughter and is she trained now?
I wouldn't compare feeding a baby to potty training for the simple fact that as long as your child is eliminating, the need is met; it doesn't matter to him or her at a very young age in which way he or she does so. In other words, your child will void regardless of a diaper or a bare bottom; on a potty or the floor, etc., etc. Obviously, if you don't offer food, (including the breast in the early months if BF) your child doesn't eat.
Finally, my daughter had a very early exposure to the toilet and everything that goes into it, as early as she started following me in the washroom, but it wasn't anything I had to train her about if that makes sense. She was probably 14+ months or so, I don't exactly remember. One of her first phrases was "bye bye poo poo" as we cloth diapered her, and she would watch me flush her bowel movements. She always loved washing her hands and listening to potty songs and reading her potty book. I naturally explained the process but didn't ask her to try or teach signs. Had she never shown an interest that young, I wouldn't have bothered, to be honest. You and I just have very different approaches, that's all.